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!
Totally worth mentioning, some LG OLED TVs are able to be jailbroken and run homebrew software!
https://www.webosbrew.org/
It can block firmware updates and telemetry, so no spying and no surprise “feature” additions.