I would say the most added value, keeping your angle, is auto-updating Linux, and assuming/handling the security vulnerabilities updates.
Now, database replication, not having to waste time to run/maintain clusters (be it Kubernetes or Elastic stack or something else), that I believe is well worth the money to offload to someone else, but even there you can get a much cheaper deal with someone that's not one of the three big cloud providers. I will also concede that Firebase is genuinely nicer to work with than its alternatives (Supabase very much included).