Not going to knock these solutions but at least for Tailscale, if I understand what I read on their web site correctly, I think it's built on Wireguard. I found Wireguard to be easy enough to configure and get working and I'm lazy and cheap.
Since then, I run my web and email servers on an old laptop in my home and the Internet POP is a $3.50 VM plus $1 for a static IP, at AWS Lightsail. This works for me but if I needed to connect a disparate office and devices together I might look at Tailscale or one of these packaged solutions, or maybe not.
you can run netmaker in a lightsail VPS. Similar functionality / UI experience to tailscale but self-hosted
Sadly not open source and their change notes are not yet production ready. Every release something breaks. I switched back to pure wireguard because of this. I also wouldn't call tailscale and netmakers ui comparable. Netmaker has far more options. Tailscale tries an apple approach by hiding almost everything but DNS.
Just to clarify this take, the source is available on Github [0] but licensed under the highly controversial Server Side Public License [1][2].
This license was originally written by MongoDB. They applied to get it recognised as an open source license with the OSI but later withdrew the application as it became clear it wouldn't have been approved.
OSI explained in 2019 [3] why it didn't consider the license to be open source.
[0] https://github.com/gravitl/netmaker
[1] https://github.com/gravitl/netmaker/blob/master/LICENSE.txt
[2] https://en.wikipedia.org/wiki/Server_Side_Public_License