The chirping-crickets have finally left me with no choice but to conclude: Opera Software can't even make its sync feature competent enough, yet?.!!?!?!!

{1-for-2 replies:
} Chronologically: No, and yes.

I was referring to the 1st and 2nd drafts of getting what-you-termed-here-as “original post” rejected without any clue as to where's the offense, Mr "@leocg".
As for Android browsers..

I'm on LineageOS so I would have to look for possibilities.
And funny that you brought-up “sync”, because that's the very reason I am having to go through this trouble.
TL;DR What happened is between this latest-device and the oldest-surviving one, I had to use a 3rd-one for quarter-past-a-year so( the oldest-device remained in irregular use and did not undergo factory-reset or any such data-wiping of sort), but after I had to give it up to somebody else after urgently finishing necessary backups, the Opera Sync feature plucks in the data only-&-only from the preceding device in which my Opera account was last logged-in[ concurrently with the oldest-one] — so even though I can very much see on the sync web that pret-ty much all of the data is fortunately backed-up for my database, the sync feature would nevertheless only prefer the lower count of load[ from my preceding-device only]. I was gonna put that question to Opera's support team directly, but since evidently there isn't any.. ...I am looking to post that as a separate thread here.

@leocg So it's a hun-percent lost-cause, eh?

Well..

Given I dunno why my post was rejected from publishing twice and this, off to some other Blink-based browser — then.

In spite of my 'very terrible' habit to type lengthy [non-work ], I'm putting the effort of making it as concise as feasible: How to import an old-browser's browsing-data, particularly from the very same browsing-engine — at the very least, to Opera for Android.

Because I do not see any option to do so. And can Google Takeout be of any material-help?

Oh-so-rarely, this official webpage is perfectly useless for those who do not use Opera on their PC, nevermind[ that] having a PC is a must. Even in 2022 when every Big Organisation is pushing only-&-only mobile "apps" on us?