So, it took... Probably as long as I expected.
But I managed to get all the collectables on Mercenaries: Playground of Destruction for #PS2
I was wrong in an earlier toot about the collectables. There is a bonus for getting all 110 Blueprints and National Treasures. After getting 110 Blueprints, you get a cheat to play as Han Solo from Star Wars.
The game was made by Pandemic, who did the battlefront games, and LucasArts was involved. So I don't blame them for leveraging some of those connections to get a cheat like this in the game. Han is unique to the #PlayStation version, I have read that Xbox players get a cheat for Indiana Jones, which is still pretty cool.
Anyway, I am glad this suffering is over, even using a map and guides. The collectables in this game are not easy to find. Sometimes, they glitch through the floor, forcing you to reload a save and pray they spawn in correctly.
At least the fun part can resume of actually playing the game!