milan,
- linkwarden can be tested at https://save.tchncs.de/
- ntfy can be tested at https://push.tchncs.de
these setups are not final yet. mind that the linkwarden browserplugin does not support sso yet (and there was a problem with the non-sso signup form).
no promise for commitment yet but, if they stay, i likely won't reset them. i wonder if the official ntfy.sh instance would also block that server once some people use it with mastodon (i expect so).