Yeah, no missables due to premium adventure. Pacing-wise, 0 juggles 2 perspectives just fine. Kiwami only has 1 character.
But if you're going for 100% you shoud know. Everything has a checklist. Unless the the process seems worth it, do not go down that rabbit hole.
You literally have to get decent at shogi, japanese Mahjong, several hanafuda games to 100%. That's on top of 5-6 different Sega games in the arcades for every Yakuza title, western gambling games, batting, bowling, racing, hostess training, darts, a fighting arena, snooker, a karaoke rythm game, fishing and more. And a billion collectibles.
Also, probably some kind of dating sim/online cam minigame featuring scanned models of Japanese pornstarts cuz Yakuza.