What are your devices? If you have Apple only, Books already does everything you need, and you need no self-hosting.
skwyckl
completely free, not self promotion
For the future: The first doesn't imply the second. In some countries, if I donate to you based on your "free" work, if it's in the same line of work you do for your main job (e.g. developer) it still counts as income.
But still, tools like these are very useful and I thank you for sharing your efforts!
I second networking. Otherwise, specialize yourself in certain fields and market yourself with respect to them. I specialized myself in some obscure GIS subfield and it brought in a couple of sweet gigs over the course of the years.
AI has been impacting the smart home industry at least since AI-powered face recognition in surveillance cameras. I think another interesting field of application is sentiment analysis, i.e. based on how you feel to automatically adjust room climate, lighting, etc. to "lighten the mood". Otherwise, the AI inside both vac and mop bots can only improve, I feel they are unimpressive right now.
I feel like this is much more than many people on here are ready to undertake.
Also, homelab is a kinda vague designation, so it stops being one when you say so. I know people who call homelabs their NAS running a couple of containers, so go crazy.
This isn't always the answer. There are people who need to use macOS because, e.g., they need to build macOS apps. Even simple building tools such as Python's
setuptools
orpy2app
requires you to be on Mac in order to build for Mac.