I worked in management from 25 and returned to an individual contributor development role at 43. There are lots of resources for developers, although not sure any of them are focused on the fact my age is a little greater than the average age individual developer.
> I look at some of my lower level engineering peers that are "stuck" in their careers (5+ years at the same level, no management responsibility), and honestly I feel like they have a pretty blissful life.
I moved from Engineering Manager "down" to Senior Engineer 15 months ago. I had pretty much the same perception as this.
Have also used Joplin. Although used this more as a personal wiki, e.g. relatively long-form notes. I would read it on mobile but rarely edit. Agree the sync there is 'clunky'.
Microsoft OneNote is quite nice.
But what I actually use most is all the Google products: Keep, Docs and Sheets. So, native app on my phone and then browser based on the laptop.
Somewhat less eminent job title though.