In terms of electricity consumption, it’s still not going to be huge, just was noted in case you wanted to go smaller. You can almost certainly go smaller, but at the same time if you already have the hardware it’s not going to be useful to sell it second hand and buy new hardware that has less performance.

Hosting static websites at home is fine if you really want to, but for anything dynamic and/or that will have a lot of users, get a vps (basically a server that you pay for storage and compute resources on and can use remotely how you like, including hosting stuff like mastodon and lemmy instances)