As an older person in a small country, no results at all come up for me. I suggest a way to find people with different or no filters. Within 4 hrs of time zone might be a good one.
This will help prevent adoption stalling because people come in and see nothing.
I think the way to grow this is to set up spaces for popular free online courses and ask those coursemakers to link to the page for that course on your site.
There are existing groups, but what's important is getting to know people who're at a similar stage in their learning, and are open to really learning together.
I've quickly booted up a Discord server here, if you or others would be interested in joining (from any geographic region): https://discord.gg/Yeavn42fBP (provisional name: Explorers)
First, I think this is an example of when it might be _good_ to find people outside your "bubble" and just filtering by demographics works against that for no good reason.
Second, if you want to filter people, timezone as already pointed out, and also spoken languages, and maybe some sort of "pace" or "hours per week" would be more practical and useful filters that are actually relevant to forming a study group.
I am on the fence about having a course-mate as I don’t want to slow down someone else (or vice versa), but might be cool to have a catchup with someone on a similar learning path for inspiration