For forensics practice I like using the NIST CFReDS site. You can download many different kinds of images.
There isn't anything too new on here for Pixels, but, I would like to see someone donate a GrapheneOS extraction image for research. We kind of made this difficult for ourselves since the OS is so secure :). A userdebug build would give the root access to FFS, but not the same.
Cellebrite and Magnet hate us, so they wouldn't do it. Their mobile forensic CTFs are great though.