Layer 2 VPN is where it’s at anyway. I want to be on my LAN not managing one device or app at a time, I never got the wireguard hype.
I was with you in principle until this part. You gave them ~30 minutes before claiming "no answer".
You can do that though? Tailscale can as well. A device can advertise subnets, and can route them through tailscale, so you just need a single node in a LAN.
This is still L3 layer though. One the main use case of L2 is proper DHCP propagation and avoid subnet collisions. I do not think that this matters in practices though. Only a limited amount of user facing service require proper L2 emulation (apple TVs ?)