I for one have a bunch of ideas that I'll probably would never find time to work on:

1. An open-source Notion alternative that works on top of sqlite files (inside browsers). Basically offline first Notion experience.

2. A webassembly powered extension framework to extend business softwares.

3. A bookmarking system that buffers my reading list and drives me to complete my research on a topic - It materialized to a level but I couldn't make it a full fledged product out of it yet - https://github.com/joelewis/readmelater

4. Port prosemirror's technology to a multi-platform stack like Kotlin - so that someday we'll have a cross platform richtext editor component that products can use for both mobile apps and web.

These are just some of my random ideas. I'm curious what others got in their bucket!