Looking it up and the ut’s all news like this:

NZBMatrix, a popular Usenet indexer, closed in 2012 due to a large takedown notice from Hollywood studios

Matrix? Are there some Matrix rooms with Linux ISO?

If you have a bit extra money, get a seedbox. Cheapest I’ve seen is €10/mo

Unless you live a very dynamic lifestyle that requires your calendar to be 24/7 synced, you can just use whatever server software you like, make it listen in LAN only, and have your devices sync when they’re at home.

DecSyncCC and Syncthing is another option.

Maybe use a filesystem and syncthing this way? https://github.com/39aldo39/DecSync

Or you could use the free tier of some PaaS like
https://render.com/docs/free if you prefer a traditional approach. Just remember to make backups, if it’s free it can disappear at any time.