OP specifically said they don’t want to dual boot, and I honestly understand why they would say that.
When you dual boot you need to worry about what bootloader is in use and how it is set up. You might find yourself in a situation where you later decide to move fully to Linux and use the old Windows drive as storage but you can’t because if you wipe it then everything stops working.
Windows has even been known to destroy dual boot setups occasionally during Windows updates.
All very solveable if you have the right knowledge, but if you want to keep your life simple then swapping hardware has guaranteed safety (nothing can go wrong with the contents if a drive if it’s not plugged in, after all) and it’s very predictable and understandable.
Wireguard doesn’t necessarily need to have those limitations, but it will depend in part how your VPN profile is set up.
If you configured your wireguard profile to always route all traffic over the VPN then yeah, you won’t be able to access local networks. And maybe that’s what you want, in which case fine :)
But you can also set the profile to only route traffic that is destined for an address on the target network (I.e your home network) and the rest will route as normal.
This second type of routing only works properly however when there are no address conflicts between the network you are on (i.e. someone else’s WiFi) and your home network.
For this reason if you want to do this it’s best to avoid on your own home network the common ranges almost everyone uses as default, i.e. 192.168.0.* and 10.0.0.*
I reconfigured my home network to 192.168.22.* for that reason. Now I never hit conflicts and VPN can stay on all the time but only traversed when needed :)