FYI, you didnt purchase the app, you subscribed to the Peacock TV service.
https://www.peacocktv.com/help/article/what-devices-and-platforms-are-supported-by-peacock
Roku:
Roku 2 (4210X model only)
Roku 3 & 4 (model 4200X or later)
Roku Streaming Stick (model 3600X or later)
Roku Express/Express+ (model 3900X or later)
Roku Premiere/Premiere+ (model 3920X or later)
Roku Ultra/Ultra LT (model 4640X or later)
Roku TV and Smart Soundbar (model 5000X or later)
Clearly, some of your Roku's arent supported - check their model #s: Settings/System/About