Sounds like that would be a good area for new Add-On Products to be developed. Pre-generated Characters and NPC's, filled out, with the pic and the sheet, would be neat, like the Rogue's Gallery. There are lots of Marketplace art packs depicting sets of NPC faces or appearances tokens, but, they do not come with character sheets or personality or text descriptions usually. In the Marketplace there are a few Card Deck add-on products which contain "characters" / NPC's with some writing, but it is written on the card images not in a Journal. Example: Elves of Mistvale, LINK: https://marketplace.roll20.net/browse/gameaddon/32
... The only area in Marketplace that currently has statted-out Characters and NPC's with filled-in text, is the Module section. Most modules have some pre-gen or pre-filled characters, either playable as PC or used as NPC. These could be used as sources of NPC's, but you're getting a lot more than just the NPC's when you purchase a module. https://marketplace.roll20.net/browse/search/?keyw
... It would be interesting to figure out which Modules have the highest number of useable NPC's.