tl;dr
What project management tool, or tools, would you recommend for a solo-developer?
By tools I mean both software, hardware and systems.

• I'm currently rebuilding my dev webpage and my more general webpage.
• I'm (slowly) solo developing a game as well as experimenting with a couple of different game ideas/mechanics.
• I'm developing a component library together with a friend.
• I'm working on my dev ops skills by having everything on a local server, including a git repository and my own websites.
• I'm also learning more about React, Web Component, ES6, C# and C development.
• I'm building a radio for my son with raspberry pi and a timetracking device.
• I'm also slowly expanding my smart home, looking for a new job, working at a dev firm, building furniture, planning a vacation to Scotland, writing a book, becoming a healthier person and, as you can imagine, I'm not sure what I'm forgetting top put on this list.

So, you know, I'm living.

I belive in single-tasking rather than multi-tasking but, especially when it comes to the development projects, it has become increasingly harder to keep track of all the single tasks I have in front of me. I constantly have to juggle many different ideas and when I focus on one project I often remember I was supposed to have done a task in another project that I forgot about and when I'm done with the current task I forget about it again.

What project management tool, or tools, would you recommend for a solo-developer?

By tools I mean both software, hardware and systems.