Yet another single point of failure.

I don't see the reason for Tailscale instead of plain old simple Wireguard, it's WG under the hood anyway.

+1

I am a relatively old school engineer. When building a bricks and mortar business recently I kept hearing about tailscale for remote access. Looked and saw it was just a wrapper over wireguard. I immediately went aha, there's a solid underlying project without the risk of something over the top trying to make life easier for people unwilling or unable to manage their own systems. Went with a direct wireguard on opnsense approach.

Bamn, proved right today.

Wireguard is perfectly elegant and maintainable as it is for me, and a wonderful improvement on traditional site to site VPNs.

This exactly. All the extra stuff Tailscale provides buys convenience, but increases complexity, the attack surface of the stack, and adds commercial components to an otherwise open protocol. Call me old fashioned but I will keep managing keys manually.