There are 3 types of Portkeys (from left to right) of varying walking distance--just like Eggs in Pokemon Go.
Prized Portkey Portmanteauteau 2 km.
Precious Portkey Portmanteau--5 km
Paramount Portkey Portmanteau--10 km
They can be found on the ground of the Overworld--same as Ingredients, but are not nearly as common.
While the Portmanteaus currently only hold Portkeys, the fact that the game specifies that these are Portkey Portmanteaus implies that future Portmanteau releases will have other Items.
There are 2 types of Keys:
Gold Keys can be used infinitely but only once at a time. Players only have access to a single Gold Key.
Silver Keys can be collected through unlocking Registry Treasure Chests and Diagon Alley. They can only be used once each.
NOTE: It’s best to use Golden keys on 2km Portmanteaus and save Silver Keys for the more valuable 5km and 10km Portmanteaus.
Since Portkeys involve purely AR environments, Players need phones with AP capabilities and a ~3x3 meter area of free space to move around in.
Players can only hold 8 Portmanteaus at a time, so it's good to cycle through them as quickly as possible to avoid missing out on the more rare drops.
Within Portkey AR worlds, Players are tasked to find 5 Wrackspurts, which are represented by glowing orbs hidden throughout the AR environment. Players can mostly find Foundable Fragments, Ingredients, and EXP.
Portkeys are mostly represented by Boots, but the other Portkey types will likely be available by the time Wizards Unite releases globally.
NOTE: Don't forget to use Potions that affect Portkey gains before stepping into a Portkey AR environment.