So while I own the Thran-Brother's War in one book, Agents of Artifice, the Teeth of Akoum novel, and all 3 Ravnica: City of Guilds block novels, I've not really jumped in just yet, knowing there's some noteworthy gaps in my collection. I don't aim to own every single novel I possibly could, but I'd like to cwnter around characters whose PoV continue a while in order to follow what's needed to be known about the current narrative (retcons or not) and my main solution seems to be "Nicol Bolas is one of the only things from back then that is relevant to this day."

So, what novel(s) feature Bolas, and starting with his earliest novel appearance, whose PoV is the story told from, and from the previous novel, whose PoV is used then?

Assassin's Blade
Emperor's Fists
Champion's Trial

Are the novels you are looking for. The protagonist is Grixis while the central antagonist is Dimir. It makes for an entertaining yarn.

Bolas then comes back in the Time Spiral trilogy which... Is going to require substantially more background.

Good to know, but who are the protagonists of those novels, and do the preceding novels follow them as well?

The one and only Tetsuo Umezawa

The protagonists in the Timespiral Block are pretty much Teferi and Jhoira as they drug around Radha and Venser on a Dominarian world tour to plug up all the rifts, guest staring almost every old 'Walker that was still alive in order to talk them into sacrificing themselves to their particular rift.

You should party like its Bolas Watch 05 and follow up the trilogy I listed with:

Outlaw: Champions of Kamigawa
Heretic: Betrayers of Kamigawa
Savior: Guardians of Kamigawa

Hilariously, those are technically "prequels."

That's probably how he likes to think of himself as well.

As it happens, I'm currently reading the Legends Cycle II. I won't say it doesn't have a few flaws and odd quirks, but it's actually pretty enjoyable. As you'd expect from a trilogy named after the Magic set Legends, it features a lot of characters from that set and somehow tries to tie them together in a meaningful way. There's Tetsuo Umezawa along with his entourage consisting of Kei Takahashi, Ayesha Tanaka and Tor Wauki. The other major PoV character, Ramses Overdark, is the antagonist and surrounds himself with more or less disposable mooks like Boris Devilboon, Xira Arien and Lady Orca. Nicol Bolas himself tends to stay in the shadows for large parts of the trilogy, though. Nevertheless, Legends II along with the Time Spiral trilogy is basically the origin story of modern day Bolas.

Fun fact: Scott McGough, the author of both the Legends II and the Kamigawa trilogy, said he tried to make Toshi's character basically the opposite of Tetsuo's. Apparently it amused him that Tetsuo would find his ancestor Toshi absolutely infuriating if he knew him.