No joke, I'm tempted to buy a Steam Deck (or true Linux phone) because... It can run a local HTML/CSS/JS app on a browser with filesystem access and audio support. This is the power of having an OS that is not locked down.
Speaking of which, what would you recommend for me to run a local HTML/CSS/JS app on a browser with filesystem access and audio support? (No, Android is too locked down to meet that spec) Other required specs:
I have an Orange PI Pro 5 16GB on a box that smoothly runs a full blown Ubuntu Desktop version and would fit in a pocket though it's maybe a little too thick (from memory the box it's about 3x5x2 cm).
Total cost was about $170.
The board itself would fit a thinner box, but you might have to 3D print one.
Mind you, a N100 Mini-PC that costs the same is even more capable as a Linux Desktop, but it's significantly larger and will definitely not fit a pocket.
You can find cheaper SBCs capable of running a Desktop Ubuntu but in my experience (with a $35 Banana Pi P2-Zero) if you go too far down the price scale Desktop Linux performance stops being smooth, even if the board is a tiny thing.
It was actually quite surprising for me recently when I found out some of these things are perfectly capable Linux Desktops.
You can probably encase a Raspberry PI with a battery and a touch screen, micro SD cards can go much higher than 16, and install Linux. Keep in mind that the Linux touch UIs aren't really great imo, the best experience I've had so far is the steam deck.