You might want to re-title your post to indicate ‘Tailscale’ instead of just ‘VPN’; Tailscale is related but as you’re experiencing, it’s more than just a mere VPN setup.
Tailscale isn’t fully supported in the current versions of the GL firmware. It should still indicate ‘Beta’ in GL GU → Applications → Tailscale.
More specifically & IIRC exit endpoints are an aspect not currently operational but @alzhao@yuxin.zou@rain or @radishman should be able to confirm as I don’t personally use Tailscale.
You should just do a more ‘traditional’ VPN WG Server ↔ VPN WG Client if you’re attempting to work abroad as ‘clandestine remote work’.
Note the first thing you’re going to want to check is if your public IP is able to connect port 51820 through your ISP’s modem into your LAN (aka: ‘port forwarding’). See a very related recent thread:
The GL docs for VPN Setup are pretty straightforward.
The Tailscale feature on the interface only provides the ability to select an exit node, and does not yet support configuring the device as an exit node.