I used the ansible method to get running and I am using the default paths. If you are also using the default paths, you can find your data in /srv/lemmy/<domain>/ . This location will hold your configuration files and your volumes directory. The volumes directory holds postgres (the database), pictrs (your image hosting) and lemmy-ui (the web-ui for lemmy). To see how much disk space you are using:
cd /srv/lemmy/<domain>/
du -hc --max-depth=1 volumes
replace <domain> with your domain.
This is great! I’m eagerly watching what people are doing with the ui.