If it something common, and you have a need for it, you both post it here in forum and also create a "feature requisition" by using the support system at help.mikrotik.com ... so it more if they believe it popular if you don't have a lot of support here for something particular. Or you'll get a "well see if we get more request", or "well see what we can do, but no promises" back from the ticket.
But I have commented they should think about how align the forum around the 80+ apps. But you just always create your own, since something has a docker-compose file (or even just Dockerfile), you can convert it their /app YAML yourself, so no need to wait for it. See 📚 Amm0's Manual for "Custom" /app containers (7.22beta+) for details on the format. I have a "online" editor that validates the schema (and if you "7.22 (editor)" is will have better support for autocomplete):
Anyway, the forum should have some category/tag/etc around /app.... Right now even the help docs still sucks, why I point you to one I wrote from experiment around in the beta of the feature (there are actually new attributes, that the editor/schema linked in my post incorporate, but the docs are missing a few now).