I’ve been printing PETG on the engineering plate with glue stick while I wait for my textured PEI plates to arrive. The one cool thing about the glue stick approach is not only does it aid in the PETG release (which is significant, because PETG really likes to grab build plates hard), but that after a few prints I can wash off literally everything with just hot water alone. Although it may look as though traces of PETG have welded themselves to the build plate prior to the wash-off, when I wash off all the glue stick from the engineering plate, all those PETG traces ultimately release and disappear altogether. No scraping with a scraper required. That’s pretty cool. The engineering build plate is magically restored to “like new” condition.
In the past, on the Prusa printer, I used the Windex sprayed onto PEI as a release agent when printing PETG, and it kinda sorta worked for me. I just wasn’t sure whether it would work on the Bambu engineering plate.