The Spectrum, along with the C64, NES, SNES, etc is still on my to-do list of catching up with computing/gaming history by devving some games for the platforms that started it all ;")
https://gkanold.wixsite.com/homeputerium/rules-2026
Some seriously great stuff in there - take the time to go through the archives, set up emulators for the winning systems, and study the results. Its one great resource for the budding 8-bit coder ..
And if you're looking for modern hardware that will get you into the scene, the ZX Spectrum Next is pretty badass - has many cores for other systems available as well, so you're not just limited to Spectrum things ..
I've personally had a lot of fun repairing one I bought on catawiki.
Bought one at a garage sale for 5 EUR. I'm pretty sure it does not work. Haven't tried it: I still have a good old CRT TV so I could.
But when people talk about coding for these 8-bit machines, they usually mean they'll target an emulator.
If you do get one, investigate that before attempting to power it up.