1. Lacto fermented food, you can spend plenty of time making unique food not available anywhere. Good niche to start is lacto fermented hot sauce. You can go very mild or crazy hot depending on your preference.
2. Sourdough is pretty understood, but there is hardly anything about gluten free sourdough. Basic principles are the same, you make a starter from flour and water, but you need to make it across different gluten free flour and combine them at the end. Endless possibilities with playing with ratios, toppings, etc.
3. Building meshcore / meshtastic nodes for your local area. There are kits / ready make nodes online or you can build your own.
4. Building a cyberdeck. You can start small with ready made parts, while you work towards designing your own PCB, handling battery with BMS, CADing everything, 3d printing, etc. You can specialise by only doing themed cyberdecks like only wearable or only fallout inspired.
5. Self host at home, but only rootless, distroless podman containers.
6. Automate all you can at home and integrate into home assistant. Install wleds, sync them to the music or use them as visual notification for things you care about