Comment by wai1234

With a supportive manager like yours, you should ask to get connected with someone in engineering who might mentor you a bit. If your current side work was driven from that end, you would quickly figure out how the culture works there and if you can get comfortable. You may have the luxury of something like an internship without the hassle.

Given the context you provide, I would suggest you try an online course or two rather than books. There are plenty of free ones but stick to those from credible sources like universities. With ADHD, you will struggle over dry textbooks. The external structure provided by a course would probably work better even with your improved health. If you start with a single self-paced course, you can go as fast as you like and avoid boredom. Burn through it in a weekend, great! Take it slower, also fine. The current lesson covers material you already know, skip it!

Ask your manager what language(s) are used at your company if you don't already know, and filter courses to focus on that for the most rapid progress to your goal.