What if that content isn't there tomorrow?

Like others have said, it's just an attempt to make selfhosting some things prettier and more user friendly while also giving you a system you could daily drive.

Honestly if you're even a little bit familiar with Linux, I would say just install Proxmox instead. It's such a good tool that will make experimenting and learning so much easier. If you still need docker then install portainer in an LXC or VM and off you go

I use the ELK stack (Elasticsearch, Kibana, Beats)

What are your thoughts on Kagi? How does it compare to Google/Bing/etc?

$10/m for 1 provider and 1 indexer?

If you hunt around this black friday you should be able to get a better deal than that. For reference I have 1 unlimited provider (newshosting) for about $30/yr and 2 indexers each around $15/yr