Just yesterday I was complaining that I wanted to SSH back to my homenet while at the office, on my office (not home) tailnet. I wrote something based on Iroh to do this, but it's one shot (ie not particularly generalized). Might be able to throw it away or redesign it with some inspiration from this! Thanks.
I solved this problem by building/running a custom tailscale client that connects to two tailnets at the same time (https://github.com/maisem/tailmix)
why not try out some existing project already on top of iroh ?
I see a bunch here on awesome-iroh page
you could try rayfish.xyz, it is compatible with tailscale nowadays so you can run both tailscale and rayfish
There's an example in the README how to do exactly that :)