Your half right. It’s not really the OS’s fault but rather the fault of the browsers and app-frameworks that use the browser in the background (electron). Because neither Firefox nor chrome have this feature implemented for Linux. The official Discord client doesn’t do it either but other ones such as Sunroof do. It’s possible that at least one Matrix client has learnt to share the screen with sound on Linux but I don’t know of any (I also don’t use Matrix a lot so don’t pay too much attention to my experience on that)

I haven’t tried it myself but the StarLite is a surface style convertible designed to run Linux, even shipping with the distribution of your choice right out of the box. And apparently it supports MPP pens. It’s not in the official specs but StarLabs is selling an active pen that’s “exclusively designed for the StarLite Mk V”

https://starlabs.systems/pages/starlite?shpxid=8d568063-b691-4a60-928b-f2a82c820093