>>57371814First: dex completions can be done whenever and rather quickly. Pogo limits available pokemon not just geologically, but also to FOMO events, seasons and all the other shit. You just cannot pursue that goal actively, you'd need to keep playing the slop for years, because that's how long you have to wait for some species to reappear.
Second: no event changes regional exclusives around. Those that do change are not even a problem.
Third: region exclusives MAY be featured during cery FOMO 2-day long "big" events like GoFest and region tours. However, last time for example these pokemon were exclusive to paid ticket holders only. Not only that, they don't give you opportunities to get exclusives from past events, so for example don't fucking expect that during Unova Tour you will get Carnivine featured last year in "Sinnoh" Tour gacha eggs. You may wait for years for them to come back and still not see them. And don't get me started on how the utter scumbags pressure you into buying incubators to ensure you will actually hatch those pokemon during the very limited time period.
Your point about raids and max battles doesn't even make any sense. They are also subject to FOMO rotations and they never address the issues above, so what makes you think it's a saving grace? If anything, they make matters only worse. You've ever seen a Comfey raid or what?
For those reasons I don't think there will ever be a reward for completing the pogo dex.