I think you're overthinking it. Wireguard is considered the "gold standard" and an excellent solution for what you're trying to do. Open ports can be a concern, but an open Wireguard port is completely silent when not in use and does not respond unless it receives the correct access keys. That makes it invisible to port scanners.
Wireguard on my OpenWRT router works flawlessly. If the router is working the WG endpoint is too, and there are no 3rd parties involved. Tailscale provides much the same thing, but as I understand it requires the involvement of multiple 3rd party services. I've been burned too many times by terms of service changes and security breaches so I wanted to avoid relying on any corporate entities wherever possible.
Tasker brings up the tunnel on my phone automatically whenever I'm not connected to my home wifi and drops it when I get back home, so my home servers are always available. My biggest problem when not at home is Verizon's crappy mobile network.
IMO it's worth the effort to properly configure Wireguard and get your servers working. Once you get it set up you probably won't have to touch it for years.