1. Use VS Code only as editor

Make sure that your .ino file is as small as possible, typically, just enough to call a second file (.cpp or .c file). The idea is that you do not need to change the .ino file often as you need to load the .ino file only in your Arduino IDE. All other files (including the .ino) you load in VS Code.

Than you edit your files in VS Code as asual, but you compile/upload the file with the default Arduino IDE. The Arduino IDE doesn't see files being saved as new, so that's why you need not to change the .ino file often, as you need to synchronize it manually.

2. MS Visual Studio

I'm using MS Visual Studio, comparable to VS Code and written stubs or even emulations for certain Arduino classes (like Arduino, but also for other libraries I use on the Arduino, which mimic or at least print something when called).

This way I can fully compile an Arduino project, and most important, run it so I can check the business logic and some parts of the hardware logic on a normal PC having a decent debugger etc. When working, I can use the first solution to upload it to an Arduino.

Writing these stubs is quite some work and the simulation can depend on the project (like for a LED strip project I actually visualized the LEDs on a PC).

3. In both above cases, I use the Arduino IDE only for compiling and uploading, not for editing. It would be also useful to skip using this Arduino IDE completely by using a command line to compile/upload using the CLI version of Arduino (see comment of theBusyBee below. In at least Microsoft Visual Studio but probably Visual Studio Code external commands can be added calling this Arduino IDE for compiling/uploading.

1. Use VS Code only as editor

   Make sure that your .ino file is as small as possible, typically, just enough to call a second file (.cpp or .c file). The idea is that you do not need to change the .ino file often as you need to load the .ino file only in your Arduino IDE. All other files (including the .ino) you load in VS Code.

   Than you edit your files in VS Code as asual, but you compile/upload the file with the default Arduino IDE. The Arduino IDE doesn't see files being saved as new, so that's why you need not to change the .ino file often, as you need to synchronize it manually.

2. MS Visual Studio

   I'm using MS Visual Studio, comparable to VS Code and written stubs or even emulations for certain Arduino classes (like Arduino, but also for other libraries I use on the Arduino, which mimic or at least print something when called).

   This way I can fully compile an Arduino project, and most important, run it so I can check the business logic and some parts of the hardware logic on a normal PC having a decent debugger etc. When working, I can use the first solution to upload it to an Arduino.

   Writing these stubs is quite some work and the simulation can depend on the project (like for a LED strip project I actually visualized the LEDs on a PC).

3. In both above cases, I use the Arduino IDE only for compiling and uploading, not for editing. It would be also useful to skip using this Arduino IDE completely by using a command line to compile/upload using the CLI version of Arduino (see comment of theBusyBee below. In at least Microsoft Visual Studio but probably Visual Studio Code external commands can be added calling this Arduino IDE for compiling/uploading.

4. PMF's comment below: You can use VisualMicro on top of Microsoft Visual Studio; this is a paid extension.

This might not be the answer you are looking for, but maybe it helps you and others. Besides, it's too long to write as a comment.

1. Use VS Code only as editor

Make sure that your .ino file is as small as possible, typically, just enough to call a second file (.cpp or .c file). The idea is that you do not need to change the .ino file often as you need to load the .ino file only in your Arduino IDE. All other files (including the .ino) you load in VS Code.

Than you edit your files in VS Code as asual, but you compile/upload the file with the default Arduino IDE. The Arduino IDE doesn't see files being saved as new, so that's why you need not to change the .ino file often, as you need to synchronize it manually.

2. MS Visual Studio

I'm using MS Visual Studio, comparable to VS Code and written stubs or even emulations for certain Arduino classes (like Arduino, but also for other libraries I use on the Arduino, which mimic or at least print something when called).

This way I can fully compile an Arduino project, and most important, run it so I can check the business logic and some parts of the hardware logic on a normal PC having a decent debugger etc. When working, I can use the first solution to upload it to an Arduino.

Writing these stubs is quite some work and the simulation can depend on the project (like for a LED strip project I actually visualized the LEDs on a PC).

This might not be the answer you are looking for, but maybe it helps you and others. Besides, it's too long to write as a comment.

1. Use VS Code only as editor

Make sure that your .ino file is as small as possible, typically, just enough to call a second file (.cpp or .c file). The idea is that you do not need to change the .ino file often as you need to load the .ino file only in your Arduino IDE. All other files (including the .ino) you load in VS Code.

Than you edit your files in VS Code as asual, but you compile/upload the file with the default Arduino IDE. The Arduino IDE doesn't see files being saved as new, so that's why you need not to change the .ino file often, as you need to synchronize it manually.

2. MS Visual Studio

I'm using MS Visual Studio, comparable to VS Code and written stubs or even emulations for certain Arduino classes (like Arduino, but also for other libraries I use on the Arduino, which mimic or at least print something when called).

This way I can fully compile an Arduino project, and most important, run it so I can check the business logic and some parts of the hardware logic on a normal PC having a decent debugger etc. When working, I can use the first solution to upload it to an Arduino.

Writing these stubs is quite some work and the simulation can depend on the project (like for a LED strip project I actually visualized the LEDs on a PC).

3. In both above cases, I use the Arduino IDE only for compiling and uploading, not for editing. It would be also useful to skip using this Arduino IDE completely by using a command line to compile/upload using the CLI version of Arduino (see comment of theBusyBee below. In at least Microsoft Visual Studio but probably Visual Studio Code external commands can be added calling this Arduino IDE for compiling/uploading.