There is nothing like this availlable currently. Framework probably comes closest, but they only sell in a few countries, and there is lots of stuff to dislike about their solutions - but building your own around a framework board might be feasible.
I have two mnt reforms - as you said, slow and expensive. They have their use for work prototyping for me, but generally wouldn't recommend. They also have the worst keyboard I've encountered in a notebook in the last decade.
About 20 years ago I made a script that converts pictures to HTML tables. Back then RAM was a severe problem for this, and even for more powerful hardware browsers tended to just crash on larger pictures.
I checked it again a few years later, and things looked way better. I guess using CSS it'd be rather trivial nowadays to do the same with a short video by just cycling through showing/hiding tables of each frame.