Wireguard is purely point-to-point. You have to manually specify any configuration involving routing more than just the local IP addresses you add.

Not sure if it's the best solution, but there's no reason to take over your entire network.

Even with my old OpenVPN setup I had a config where only my local 10.2.0.0/16 got routed over the VPN, everything else went straight to the outside world. Set up IPv6 ULA and you don't need to worry about IP addressing conflicts.

Not really? I mean, it's easy to set and forget which subnets get tunnelled with wireguard (and others, it's just that wg forces you to be explicit about it)