I can relate to almost every part of your post. I have ~13 years of professional software development experience and have also wanted to build a side project with nice-to-have extra income.
In the past, I have tried a lot of silly ideas. Recently, I shipped a web app but marketing scares me so I currently have 1 user other than myself. Here are my unsolicited tips that a younger self would have found useful:
- Stick with building software, since that's something I am good at. Not e-commerce, podcasting or becoming a Youtuber.
- Build something that fixes a problem that you yourself have. At the very least, you have one customer after you ship.
- Build small bits of features every day or at a semi-regular interval at your choosing. I did this and was amazed at the progress made after 1-2 months.
- Keep the infrastructure simple in the beginning. For example, rather than paying $x/mo for an email with my custom domain, I use an email alias such as forwardemail.net or simplelogin.io. Use as many services with generous free tiers as possible.
- Stop worrying about similar products out there until after you ship yours. I personally have stopped trying to look for similar products (or tune them out when I see one) and focus on my own instead.
I'll plug an idea if I may - I have been thinking about starting a chat group with other developers working on side projects. I myself am a solo dev looking for support (while also working a full-time day job). If this is something that you or others in this thread are interested, please let me know. My contact info is in my profile. I have tried searching on hn for such support groups without much success; there have been interest in the past but they are many years ago.