For others, it’s a “yes on paper” situation. It will probably often not work out of the box, but it seems likely to be possible as an advanced configuration. At the end of the line of possibilities, it would definitely be possible to set up a couple of docker containers as one-armed routers, one with your VPN and one with Tailscale as an exit node. Then they can each have their own networking stack and you can set up your own routes and DNS delegating only the necessary bits to each one. That’s a pretty advanced setup and you may not have the knowhow for it, but it demonstrates what’s possible.