Android

Firefox on Android is really nice and meets most of these. Also having full extension support is a huge plus.

I use fennec, it's just firefox without current bs of firefox going on

Ironfox is nice, thats what I personally use. Its more secure than base Firefox (and importantly for me its in Accrescent)

Firefox is by far the best Android browser.

Don't think I've ever used the default Samsung browser... Not intentionally, at least. Firefox Mobile has been fine for me. It has basic plugin support, do you can run unlock origin with it, too.

Have you tried Waterfox? It satisfies most of your requirements, I believe.

regardless of your browser choice make url check your default link handler to unshort urls and remove query parameters

I use duck duck go browser as my main and default browser, and I press the burn it all button regularly. It offers to exclude sites from the data purge if you log in, but for the three or so websites that I want to stay logged in to fill time, I just use Opera for them.

I use Ironfox and Fulguris (for when something doesn't work in IF). They're both good. Ceno is also interesting for its p2p/ anti-censorship features, although it's slow when not on wifi.

I'm going to suggest an alternative to Samsung Internet or Firefox : https://github.com/uazo/cromite

Out of the options I've tried, it's probably the best bet for reducing tracking, fingerprinting & increasing security without turning to Tor browser (which while it is more anonymous, is frustrating for general browsing)

For clearing cache, there are two options. There's a dedicated clear browsing data button in the hamburger menu, it can also be configured to "sanitize on close" (similar to Firefox on desktop, or Brave on desktop / mobile) [In cromite, this can be found under Security > Clear the data at open]

I can't recommend Firefox on Android in good faith, until site isolation (fission) is enabled on the platform. This is a major security regression compared to desktop Firefox, or chromium based browsers on Android

Edit: It seems like Iron Fox (continuation of Mull / fork of Firefox) has site isolation enabled - but it is still buggy and does not have all features enabled e.g no isolated process SELinux labels.

Samsung Internet is my favorite, but I am also a lil weirdo. Firefox is my second favorite to merge between devices, as well as connecting with the Pocket app to save things for later.

Im not sure if it is foss (have to check) but Soul Browser is my favorite. Packed with features and highly customizable, most if not all of your requirements are possible within this browser.

the quit button must clear cache and close all tabs, so I think it should be native and not an extension, but maybe I'm wrong?

This is the closest Firefox add-on that I could find: Essential Buttons Toolbar and Homepage

Probably an unpopular opinion but if you want absolute minimalism without ads use Violoncello text browser!

cromite