Hey, you may create a post with #introduction telling something about your interests. You can search for the hasthag to get some inspiration
Also: I can recommend https://gup.pe/ this kind of a group thing on mostodon. there are not many groups yet. but maybe it is a starting point for you. on the website there are details how it works.
Since you are on a small Mastodon instance, you will see more people the more connected you (or your instance) are.
You can paste virtually everything in your profile's search field and interact, e.g. https://mastodon.sdf.org/@bkhl/103034141134472687
Ein kleiner und kuscheliger Mastodon Server für friends und family.