Both manifest v2 and uBlock Origin are supported in Vivaldi.
They're deliberately keeping them alive.
My only gripe with Vivaldi is the implementation of its UI. The whole thing is basically a Webapp.
On low-end machines the performance can be quite bad, and even on modern ones, there's an overhead that I'm uncomfortable with.
While not specific to Vivaldi, the software world as a whole has foolishly pivoted away from native toolkits for the sake of convenience, laziness and a fair bit of sheer incompetence.

Your modern distros probably run on extremely fast Nvme SSDs and high core-count CPUs that until fairly recently weren't really that common. I'd say they started trickling in at about the same time the whole SystemD transition was set in motion.
I'm running several non-systemd systems and frankly can't feel a difference speed wise for better or worse.

Or just Devuan...

Slackware can do that and more.
It's always been a rock solid, sane and as true to the Unix philosophy as you can get in the Linux world.
I think it's being unfairly ignored by the wider community for no good reason.

You pretty much nailed it there.
I keep finding myself in this position, and frankly, I usually end up installing Debian... and suffer. :)

That's actually bad news.
It doesn't increase privacy. What it does increase is dependency on a single entity.
They're redirecting queries to their partners while bypassing the local DNS configuration.
Mozilla centralizes the net. Not cool.

Without the/any store?

Hopefully they'll regain a focus on desktop usage.
That Smartphone/PC hybrid thinking has hurt Windows quite badly.
The desktop UI is different and has a different functional purpose. Connect the two, don't merge them.

(that goes for modern website design as well)

How I wish I had a x64 Win2k with HiDPI scaling and support for modern hardware.
Win2k was the best no-nonsense version of Windows.

MS-DOS was based on QDOS, a CP/M clone made by Tim Paterson. They (famously) bought the code for 50k$.
Both Apple and Microsoft "Stole" the GUI idea from Xerox at more or less the same time.
MS had a failed dance with IBM at the time developing OS/2 which also used the same GUI principles, that lead to the seemingly "late" arrival of the Windows GUI.

Those spam messages weren't from Libera.
Just trolls trying to stir things up

Edge while certainly not ideal in any way is actually a better chrome than Chrome.