I have a few computers at home. I'd like to access them securely from anywhere in the world. WireGuard makes that easy.

Same, but also various project computers on various WiFis that autoconnect to my WireGuard server.

Have you tried zerotier? No server required.

It basically replaces IPSec. You might want to look that up. There should be plenty of information regarding that.

A fairer assessment is that it replaces ESP (the stream encryption portion of IPSec) and a small subset of IKE features. If you look at the ecosystem of software arising around the core Wireguard protocol, much of it is a [poor] recapitulation of IKE.

Key management and PKI in particular, not bulk encryption, is the hard part of IPSec (in so far as its hard), and Wireguard doesn't actually solve that. I wouldn't be surprised if someone eventually hacked Wireguard configuration management into an existing IKE daemon.