I also came across a browser named Dolphin and the Tampermonkey (again?) add‐on for it.
As it’s again something for Android, I cannot test right now.
Wow I’m impressed!
PINNED SOLUTION!
I could test this with an Android device (model Samsung something) and wow.
Tampermonkey alone at first did not work for mb. COLLECTION HIGHLIGHTER so I thought it was helpless, until I tried mb. FUNKEY ILLUSTRATED RECORDS and wow those thmbnails all showed up before my eyes, I could not believe it!
So, as Tampermonkey’s browser is minimalist crap, I decided to test Dolphin+Tampermonkey as Dolphin looked like a full featured browser.
So I went on and installed mb. ALL LINKS, mb. COLLECTION HIGHLIGHTER and mb. FUNKEY ILLUSTRATED RECORDS, all that.
ALL LINKS worked out pretty well, as you can see, only Wikidata‐to‐Wikipedia doesn’t work (perhaps because of some cross‐domain restrictions that could be lifted up, but no time for further research), I don’t know why:
Know that the background tab is actually loading the collection (41%) in the background, the COLLECTION HIGHLIGHTER script is — like in Opera 12 — not paused when in background! 
Now here is the COLLECTION HIGHLIGHTER loading in foreground:
Here is FUNKEY CAA working on my collection first page:
And here are both FUNKEY CAA and COLLECTION HIGHLIGHTER (once loaded) working at the same time as ALL LINKS (but off screen):
I report this case as a working solution in my first post, which I have turned into a wiki if you want to reference other working solutions yourself, in the future.