This is a Just-in-Time (JIT) access request web app. It's like
https://github.com/tailscale/accessbot but without the Slack bit and
instead being a webserver.
It's a tsnet webserver, so it
knows who you are already and which device you want access for.
The hallpass server is a tsnet web application
that allows users to use request instantaneous, time-bound access, known as
just-in-time access, to Tailscale resources from other people in their
organization
It is effectively the web-based version of github.com/tailscale/accessbot.