Having an easily-searchable version-controlled record of my "things I'll have to Google again" has been incredibly useful for me.
The current incarnation of my "lab notebook" is here, and as of today 1002 days old: https://serhii.net/dtb
The most surprising thing for me was it's ROI was much higher than any other bookmarking / PKM stuff I tried, and I tried a lot. I had/have a semantic mediawiki for links, with tags, categories, estimates of complexity and ratings etc etc etc, but apparently searching through a long textfile or browser page is still much faster
I have something called "Diensttagebuch", which is awkward to translate ("Duty diary"?), it's a Jekyll blog (currently at https://www.pchr8.net/d/dtb/) for things I know I'll have to google later. I have two bash scripts for creating-or-opening a new page and for deploying (upload to server + commit to git). I use https://github.com/rking/ag.vim for searching though the Markdown files on my local machine.
For more general knowledge, Semantic Mediawiki (http://pchr8.net/f/), but it's basically a big link database now. I can sort it by rating / complexity / to read / domains / keywords and found it quite flexible.
I'm on arch and Firefox 66.0.1 and for me the Private windows do share a session. Containers also fixed it for me, but when I discovered this it was very unexpected