Aside from Wireguard, you have Wireguard alternatives-but-not-really-since-they-are-based-on-Wireguard like Netbird and Tailscale. The latter is more well-known, but the main downside is that, to connect to the cloud servers, you need a Google, Microsoft, or Github account to login. It can be self-hosted with Headscale (community project) though! Netbird is similar to Tailscale, but you can use normal email login to use their cloud servers, and they offer official self-hosting support.