For context, I have been using Vim as my main driver for 12+ years, now, and I have been heavily involved with the ecosystem (patches, plugins, support, etc.) for most of that time.
Learning enough Vim for it to pay off in terms of productivity and whatnot is quite a journey. If you are committed, it might take a couple months to follow chapters 1-12 and 20-32 of the user manual, which will put you in a better position than most Vim users. If your goal is really to be able to use Vim for Go and Rust projects, then there is no way around that first step, but if you somehow don't go all the way, then what you have learned will surely come handy next time you have to use Vim so there is no loss, here.
> do you think it's worth the effort to learn using VIM more deeply today?
I did that and I really love where I am. Will it click for you? I have no idea.
> If yes, do you think VIM is still fine, or rather neovim? Or something fresh like helix?
- Vim (not VIM) has been in active development since 1991 and it is not showing signs of slowing down. It is more than fine.
- Neovim is merely a fork with different goals. At a low level, the two tend to diverge more and more but when it comes to the core user-facing stuff like Ex commands, modes, operators, motions, etc. there is practically no difference.
- Helix seems promising but it is far less ubiquitous than Vim.
Everything is worth learning, whether you have an immediate use for it or not.