Testing my websites on https://www.websitecarbon.com/ - they come out pretty well, better than 93% of other websites. Some of that is down to having a green host that uses mostly renewable energy, and some down to using really light code.
Amazon UK is pretty high carbon, as is Youtube. Mastodon is somewhere in the middle.
The Wandering Shop is a Mastodon instance initially geared for the science fiction and fantasy community but open to anyone. We want our 'local' timeline to have the feel of a coffee shop at a good convention: tables full of friendly conversation on a wide variety of topics. We welcome everyone who wants to participate, so long as you're willing to abide by our code of conduct.