People have different expectations to computers nowadays. They aren't isolated curiosities any more, you can't capture the environment of the 1980s home computer revolution.
If you do want a similar experience (at least superficially) to a spectrum 48k, get a Pi 400, don't connect it to a network, but don't expect the same outcome as you had -- the world is different, there are very different things competing for attention, and different rewards for time spent.
If you do want a similar experience (at least superficially) to a spectrum 48k, get a Pi 400, don't connect it to a network, but don't expect the same outcome as you had -- the world is different, there are very different things competing for attention, and different rewards for time spent.