I tried setting up Tailscale on my UDR. I found https://gist.github.com/lg/6f80593bd55ca9c9cf886da169a972c3 was a good starting point with some adjustments. Unlike the EdgeRouter the UDR is apparently an arm64 device so I downloaded static binaries for arm64 and extracted them to a temporary directory. I copied the files to their proper locations like this:
cp tailscale /usr/bin/tailscale
cp tailscaled /usr/sbin/tailscaled
cp systemd/tailscaled.defaults /etc/default/tailscaled
cp systemd/tailscaled.service /lib/systemd/system/tailscaled.service
mkdir -p /var/lib/tailscale
touch /var/lib/tailscale/tailscaled.state
chmod 0400 /var/lib/tailscale/tailscaled.state