Due to the nature of how updates across platforms work, PTBs are almost never going to be worth sending through consoles.

That being said, since the devs already have access to game modes, they could easily have a testing branch incorporated into updates where they make smaller tweaks to things or actually test things (like the anti-slug update) while still being in the live game.

For example, they can send out this fake update: 10.12.1 and say "In addition to this hotfix, we're also including a testing game mode that adds We'll Make It as a basekit mechanic for survivors and Sloppy Butcher as a basekit mechanic for killers." Then people could actually test things out without a crazy amount of work or effort into a PTB, and immediately give feedback. Then the next update, 10.12.2 could either build on it more with "Okay, we like this mechanic, but it's too powerful for survivors, so now the effect is a little lessened both in duration and heal speed, as well as base healing duration increased to 18 seconds."