Not sure of maniphest jargon, but I see that this was accepted for inclusion. Does this means that zerotier package is work in progress?
I fear the official instrllation script, oriented to the main distro (deb, rpm, bsd, etc.) because it could break solus.
I prayed Freya but it seems she's around with her cats.
This has sat in accepted for inclusion for 6 months now. Clearly, there is a lack of demand for the inclusion of this software, nobody has stepped up to provide a patch, maintain it, and properly integrate it. Closing as a result. Feel free to reopen but only when someone offers a patch via our proper patch submission methods and volunteers to be maintainer.
All the information you're after is already in this task. The request to include it has been accepted but no one has stepped up to do the work to package it for Solus and become the maintainer. So the task is closed until someone does so. To be clear you don't have to be a Solus team member to do this. If there was any other news, it would be noted here.