There are signs that onioncat may still be alive. This doesn’t change anything on the documentation side but good to keep an eye on.
OnionCat is definitely alive:
Last blog post - late August 2019
Last commit on GitHub - 9th December 2019
Maybe it is possible to connect to Freenet without the use of a VPN after all (see related Support thread topic)
It’s alive, but it doesn’t have the same security guarantees on v3 and v2 is about to die in a year or two. Meaning there’s more configuration needed to work with v3 and you must consider your machine exposed to the public network as the private mechanism doesn’t work like it did for v2 because addresses are longer but the IPv6 addresses assigned to onioncat are significantly shorter.
TL;DR yes it is still useful. It was reinstated in Debian, consider stuff on your machine publicly accessible with v3.
According to a Tor dev v2 services are already not secure and are EOL:
v2 addresses are 80-bit and can be
literally brute-forced and impersonated with the current human
technology, so their deprecation is already too late.
I think we should remove any instructions for v2 and update any legacy ones for programs to use v3.