There is a raspberry pi kit to do just that (keyboard + screen + computer all in one).
The only other option is a ZXSpectrum Next (Kickstarter that is having trouble with supply chain right now for the latest batch). It's freaking awesome though. You can directly download new spectrum games from the internet or just use the SD card. Someone wrote a new assembly language book. There is a BBS app...so many cool things going on. The commander x-16 will also be cool if it ever comes out.
The only other option is a ZXSpectrum Next (Kickstarter that is having trouble with supply chain right now for the latest batch). It's freaking awesome though. You can directly download new spectrum games from the internet or just use the SD card. Someone wrote a new assembly language book. There is a BBS app...so many cool things going on. The commander x-16 will also be cool if it ever comes out.