I've also thought about buying a second-hand server (I even find it at interesting prices), but to make it publicly accessible - for some projects, it can be more complicated in terms of stability and internal security.
I wouldn't self-host anything Bitcoin related from my home.
I wouldn't want my home IP open to the public either, but I was wondering if a remote web server with a WirdGuard client and local server hardened with nftables would be a safe way to have specific local services/ports accessible from the remotely hosted domain name. I'm only just starting to learn about using nftables for security, so I wouldn't risk it with my current knowledge.
I've already explored this topic a bit. Well, once configured, it's possible to isolate the network to protect home equipment from the outside world.
But I think the biggest problem, besides ensuring a good initial network setup, is its maintenance. It requires the person to always be very attentive to what is happening on the network, to check for updates, and to keep security levels at the highest possible level. Sometimes an update can ruin a configuration, which needs to be completely revised to maintain the desired levels.
So it's about stability. Ensuring it's 100% online, that it's not under-loaded. We are not 100% home to guarantee this supervision. There may be power outages, and other external factors of that nature, that can affect the entire structure, even if it is properly constructed.
Impossible? No, it's not, but it requires a very high level of "work" to ensure that everything is always functioning properly.
Ultimately, the question remains: is all this work and risk worthwhile, just to save money on a server that guarantees all of this?