Improved Unarmed Strike or Heavy Armor Pro

[René P]

Any ways I can get my toon either of those feats... without having to use a feat? Items, classes, archetypes etc.

[Master of the Dark Triad]

Yeah, lots of classes have heavy armor proficiency...

A dip in fighter will get you that, along with a bonus feat.

Then, you can use that bonus feat for improved unarmed strike.

[Kazumetsa Raijin]

Unarmed Fighter or Monk would give you IUS.
I'm not sure about Heavy Armor Pro