How to submit suggestions for Trisquel, preferably without using <em>GitLab</em>?

I don't know how GitLab works. When you sign up / register at https://gitlab.trisquel.org/, I assume what actually happens is you sign up with GitLab rather than Trisquel. Is that correct?
Or is https://gitlab.trisquel.org/ mostly a Trisquel-internal thing, you're not registering with GitLab, and your data won't go to them?

Is it OK to suggest Trisquel adopt an additional package into the repositories?
Where can you submit such suggestions? What are good / bad channels? Contact form, GitLab issue tracker, forum, wiki, …?
Can I submit without using GitLab?
And how would I know? I've tried to search for guidance but failed to find any, so I used the contact form. No reply yet, perhaps because only one week has passed.

Thanks in advance.