Go to pasture.funfedi.dev and follow the instructions.

I believe that

curl -o fediverse-pasture.zip\
    https://pasture.funfedi.dev/assets/fediverse-pasture.zip
unzip fediverse-pasture.zip
docker compose --file fediverse-pasture/mitra.yml

should bring up a mitra instance at http://localhost:2976/ with credentials admin, password. You need to wait like 1 minute for the database and server to start.

Akkoma should work as easily as well. http://localhost:2975/ with credentials witch, password, but start up is longer. If you run both, you can message each other.

Mastodon runs a lot of vite nonsense, I don't have energy to look at, gotosocial's frontend didn't work last time I checked, Misskey and Sharkey work, but are awkward due to how their tokens work. No other details come to mind.

Final note: These docker files are made to be easy to start and destroy. I don't know how well they act if one keeps them running longer than an hour.