electrons actually loop around in a closed DC circuit in the speed of light

On average, electrons “move forward” much much slower than that:

https://en.wikipedia.org/wiki/Drift_velocity

But even the whole “electrical signal” is slower than the speed of light:

https://en.wikipedia.org/wiki/Velocity_factor#Typical_velocity_factors

Maybe with Xpra you could do something like that

At some point, uppercase letters were written without accent in French. I’m unsure where this comes from, but I heard this was due to the limitations of printing presses, and then typewriters kept the convention.

In any case, the style is quite out of fashion today, but I know people who still write (handwriting and typing) without using accented uppercase letters.

Maybe look into PipeWire, Reaper in jack mode works fine connected to PipeWire for me, without any of the problems you mentioned.

It is quite possible that your desktop audio already uses PipeWire depending on your distribution, you would need to look at latency settings if you want live playback.

A lot of fun so far ! Thanks for making this

Open source Not […] allow […] commercial applications

For some definitions of open source, this is contradictory (FOSS). Some non FOSS licenses do limit commercial use while making the source available, this could be a possibility for you.

But, I’d instead recommend that you check if a copyleft license such as the GPL provide enough protections for your use case.

I don’t have the information regarding xmodmap, but here are two other options which I am using if you are interested.

• With the compose key set, you can hit / = to get ≠. Or you can set custom sequences in .XCompose, but I don’t believe you can get the exact combination you suggested.
• Use a virtual keyboard manager such as KMonad

I recommend https://github.com/kmonad/kmonad

Great resource, thanks for sharing