For Honor Collectible Locations (Observables & Breakables) in all Samurai Chapters (3.1 - 3.6) for the trophies Lore Master & Hooligan.
There are 83 Collectibles scattered across the 6 Samurai Campaign missions. A total of 48 Observables and 35 Breakables.

In total the game contains 235 Collectibles scattered across 3 campaigns (144 Observables and 91 Breakables).

To unlock the "Lore Master" trophy / achievement you must find all Observables in every campaign (Knights, Vikings, Samurai). These Observables are certain objects in the game world that you can look at and press L1/LB to hear some lore.
For "Hooligan" you must destroy all breakable objects across all three campaigns. They look like barrels and are pretty much in plain sight.

The collectibles are saved instantly upon picking them up. All progress is saved on the online servers right away. There's no need to reach the next checkpoint and you don't have to pick them up again if you die.
In mission select you can see exactly how many you found in each mission. None of them are missable, everything can be collected via mission select at any time.
All the collectibles are sitting right next to each other and very quick to collect. The missions are short and the maps very small, so this won't take long at all.

As a nice bonus you get a new emblem for each mission where you find all the collectibles (collectable reward). These can be used to customize your character.

TIMELINE SAMURAI CAMPAIGN:

3.1 Duty - 0:05
3.2 Thinning The Herd - 3:13
3.3 Picking Up the Pieces - 6:44
3.4 Unity - 9:06
3.5 Honor - 11:54
3.6 Apollyon - 17:18