Used to have an interest in exploring the land where I lived, map-making, and looking for edible plants to gather and eat purely for the fun of it. Also kept a journal detailing every new plant and animal species I came across, but then I moved closer to the city and that sadly killed the budding hobby. :'I
Nowadays, the only unusual interest I can think of at the top of my head is maybe my music tastes. Not that what I listen to is especially crazy or niche, but that I listen to such a wide range of stuff and genres. I'll listen to jazz, hiphop, pop, country, electronic, lofi, opera, rock, metal, psychedelic trance, citypop, and reggae in one sitting, in a bunch of different languages from different decades.
I like to be surprised by what my randomized playlists throw at me next, and sometimes make a game of it by challenging myself to see how long I can listen to music without having any one language (or other category) come up more than once in the list. I strongly associate songs with memories and feelings and like to imagine a different dreamscape or story scenario for each song.
Sometimes music is a background thing, but can often be a pastime in-and-of itself for me.
Might not be such an unusual thing to the creators I interact with over the internet, but among my irl family and acquaintances it's something I've resolved to keep to myself after being called weird one too many times.