I'm pretty much sure only free option for finding out what other people search for is Google Trends. It's very valuable data that is hard to get, so the companies that offer it charge quite a lot for it.
Here are some of the things I self host that I haven't seen mentioned:
Continuwuity is a chat server that talks Matrix, so you can join the chat rooms of a lot of open source projects or make end to end encrypted private chats
Forgejo is a self-hosted code forge (github alternative) - very useful
FreshRSS is a good one if you like to follow blogs, newsletters or pretty much anything 'news'
Grafana plus VictoriaMetrics and/or Quickwit is very useful for keeping track of the health of all your services
Homepage is a... homepage for all your services
Stalwart gives you a mail server. Set it up for any other projects that need to send mail, or as a backup for your emails, contacts or calendars - it's the easiest way to set that up self hosted. Making it suitable as your main email may need more effort (delivery).
Related to Continuwuity / matrix, you can set up the Mautrix collection of bridges, which let you bridge Discord, WhatsApp, IRC, telegram, and more into your matrix account or chats seamlessly.
LMS (lightweight Media Server, not to be confused with Logitech Media Server) is an alternative to Navidrome that I find works better with my library tagging and ListenBrainz
Speakr - audio transcription with diarisation. Very useful if you like to record meetings.
My personal selfhosting repo is just about 2 years old with 750 commits now, and probably more than 60 containers running. It's not because of one great effort or design or anything, just setting up a service or two when I find it interesting every few weeks, and trying to make all my setup consistent. Almost everything is deployed as a container run by Podman quadlets, files mounted in /var/opt, config etc copied into place by an ansible script. But not everything, sometimes getting it working was easier without the sensible or I needed to do some funny networking.
TLDR: Coming back again later, and making that easier.
Email is federated. You can set up your own server using something like Stalwart in a few hours. I deliver thousands of emails a month on my personal server. The problem is deliver ability to Gmail and outlook, but if you don't care about that then you're golden.
The clue there is 70% goes to labels, not artists - large rightsholders who already have wealth taken a massively disproportionate amount of that, so the artists you listen to get fractions of a penny. They make far more when you buy a CD or go to a concert.
Last I visited, Barcelona was beautiful and the people living there adored it. London isn't terrible either, although housing is extortionate due to 'investors' and landlords
All of the other answers mentioning coturn here are wrong - your friend is trying to call you using element call, which needs an instance of a livekit and a JWT micro service to grant permissions to use the livekit instance. You can use a livekit cloud account, but you do need to host the JWT service. I would suggest looking up Element's documentation
Actions is significantly better, there are lots of subtle UI improvements, there are new importers, etc. Not a killer feature, but many small improvements that add up.
MusicBrainz Cover art is from the Internet Archive's Cover Art Archive, and you can edit it easily via the musicbrainz.org website. You can also use https://harmony.pulsewidth.org.uk/ to update the medatata with stuff from streaming sites automatically.
Alternatively, you can install a plugin from Picard to download from, for example, Deezer or Apple Music. You can also grab a plugin to do replaygain, to get a more normalised audio volumes, like on streaming services.
For local music recommendations, you can try experimenting with listenbrainz local right now, if a bit experamental. It is essentially the Listenbrainz recommender on a local library. Building a better system for local music is on the MetaBrainz team's mind, and my final year project for University is going to be related as well (maybe follow me for updates if you're interested). I don't think automatically downloading from Spotify or whatever will happen though because of legal issues with that - maybe there'll be the ability to add plugins to do that. However, you can use the MusicBrainz database to get the exact Spotify link for many tracks (thanks to the Harmony importer lol). Ideally sharing libraries with your friends would be possible, though.
If you're not bursting you didn't have fish and chips