The blog post was a good read, you have a way of writing that feels pleasant to me. It touches some areas with which I’m familiar, and others with which I’m not. It was interesting to learn a bit about the Traefik proxy and Authelia authentication!
A tip; you had this bit, where you use sed to edit vsmagent.hconf:
$ sudo sed -i "s/^agent_hostname=.*/agent_hostname=$(curl -s http://icanhazip.com)/g" /opt/thinlinc/etc/conf.d/vsmagent.hconf
I would like to recommend using the tool tl-config which would allow you to simplify things a bit:
$ sudo tl-config /vsmagent/agent_hostname=$(curl -s http://icanhazip.com)
Note that, as mentioned in tl-setup, you will have to ensure that sudo has ThinLinc tools in PATH first. Otherwise, tl-config is found at /opt/thinlinc/bin/tl-config.