Yes it is a spiritual successor to BG2 and if you add some story elements and some more budget it could have been called BG3.
I suppose that depends on what you liked in BG2 and what BG2 was for you. I have a soft spot for Pathfinder and even backed the sequel as I think company has a heart in the right place, but that said, from what I played I thought Kingmaker was pretty bad. As a spiritual successor to BG1 - I might see it. As a successor to BG2 - definitely not.
BG2 laid foundation for what became Bioware RPG - a story driven, character driven RPGs. While people praise BG2 for it's "simulation" 1) there wasn't much of it 2) I really don't think that was Biowares intent - at least not in the end. While it's complexity and scope blew me away at the time, looking back at BG1&2 and comparing it to other RPGs I think streamlining was it's biggest success, not complexity. For a long time I thought Bioware took a drastic turn with KOTOR forward, but nowadays I think that was always their intent - or at the very least least they reacted to what really worked in Baldur's Gates - more and better voice acting, set story arcs for companions, strong narrative and villain, defined protagonist, bigger focus on presentation of the story with limited but impactful imput from the player.
In that regard Pathfinder is really really awful. I do like it's commitment to some systems though - like resting and time management. I don't think they are well done or interesting - like assigning resting duties isn't an interesting system to interact with (on second thought - not many of them are). From gameplay standpoint (again) I thought both PoEs did it better - easier to use, more choices to make, better impact. However, there is in-world consistency to it, characters doing chores, that I found it really compelling. Also banter was nice, even if nothing of worth is being said, and I loved that you actually set up a visible camp on the location if you rest in "tactical" view. That is something I would like to see in BG3, I think, instead of generic camp ala Dragon Age:O. But dialogues trees are some of the worst I have seen in a long time, and I am not talking about tone - I like the lighter tone.
