It probably would be easier to just write an “update Caddy” script. They don’t release updates very often, except for security fixes, so it’s not much effort to do manually. I automated mine with Forgejo Actions, you could do the same with GitHub actions as a free option for example. Lots of neat ways to accomplish this!

Xcaddy is a build tool. Caddy plugins are built into Caddy itself for optimization purposes, so xcaddy essentially makes you a custom version of Caddy. It only conflicts with Caddy so much as building a new version would conflict with the old version. You still get a normal “Caddy” executable after running xcaddy, just replace your existing Caddy with the new one created by xcaddy!