Another solution I don’t see mentioned (yet) is have both ends connect to a VPS running your WG endpoint. Then both sides only have to have egress ability, nothing coming in, no CGNAT to worry about.

Negative. All done in uptimekuma/HA. You’ll need an access-token from your home assistant server but it’s pretty straightforward.

I use uptimekuma with notifications through home assistant. I get notifications on my phone and watch. I had notifications set up to go to a room on my matrix homeserver but recently migrated it and don’t feel like messing with the room.