Tailscale does do something along these lines, but it's kind of surprising... If there is a tailscale route announced, it will take precedence over other routes, even if they are more specific. The primary use case for this seems to be if you are at a coffee shop, you can access a tailscale routed network that has the same IP range as the coffee shop.
The down side of this is that if you have, say, a wider announced network routed over your tailscale (say 10.0.0.0/16), and then you have machines within that network also connect to the tailscale (say a machine with 10.0.1.1/24), it now will try to reach machines on its local network interfaces via routing over the tailnet. Pretty unexpected.
The down side of this is that if you have, say, a wider announced network routed over your tailscale (say 10.0.0.0/16), and then you have machines within that network also connect to the tailscale (say a machine with 10.0.1.1/24), it now will try to reach machines on its local network interfaces via routing over the tailnet. Pretty unexpected.
https://github.com/tailscale/tailscale/issues/6231