I've now switched over to Safari, with content blockers, my password manager and 1 Blocker to block ads.
It seems like Apple is the only company that somewhat cares about user privacy, every other company would trade their users' data in for a quick buck.
Any other open source browsers that are just browsers?
Arc https://thebrowser.company/ - Perhaps not open source?
Orion https://browser.kagi.com/ - Mac only (built on webkit)
Vivaldi https://vivaldi.com/ - Chromium based
Opera https://www.opera.com/ - Chromium based
Ungoogled Chromium https://github.com/ungoogled-software/ungoogled-chromium
There’s also OmniWeb, which apparently isn’t actively developed, but still receives test builds
https://omnistaging.omnigroup.com/omniweb/?pk_vid=f30b228392...
Pale Moon is back on MacOS
https://www.palemoon.org/download.shtml
You can try Qutebrowser
Or why not go totally bleeding edge and run the Servo test builds
https://github.com/OtterBrowser/otter-browser
Ungoogled Chromium
The Android version https://github.com/macchrome/droidchrome/releases comes with customizable adblock filters e.g. easylist, I don't care about cookies, EasyPrivacy etc. that I'm no longer forced to put up with Firefox's jank just for some decent adblocking on my phone anymore.
I use it when I need a browser that I could focus while using.
Thorium on desktop, definitely the best and fastest Chromium derivative.
Cachy Browser is good if you are on an Arch based linux distro.
There are a lot of "bespoke" options here, but if you want privacy for your mom, it's going to have to come from a mainstream source. Economies of scale is an important consideration.
I think it's worth considering that you're gonna have a hard time supporting 20 million+ lines of code without the overbearance of capitalist corruption.