D&D General Reincarnate is and has always been, weird.

[Voadam]

Wouldn't Ookla the Mook essentially be a Bugbear?

Physically as far as stats? I don't remember a lot of stealth and surprise from Ookla, but yes, most hulking brute reskins could work for most of the stats.

Couldn't you use that to modify their lore?

If you rewrote bugbears to narratively be a version of a Thundar Mook or a Star Wars Wookie (which Ookla is based off of) that would be different social interaction dynamics than the cowardly, greedy, bullying ambush brutes who are used as a terrorist special forces part of hobgoblin armies and it could work. You'd probably lose most of the D&D/Pathfinder narrative bugbear theming about being fear feeding and ambushes and the intertwining goblin interactions, but it could work.

Chewie can walk into a Tatooine cantina, hang out, and make a deal with Obi Wan Kenobee. You don't expect Chewie to hide under a child's bed to do jump scares the way an encounter with a bugbear goes in one of my Pathfinder adventure path modules.