Alexander Wirt (formorer) mentioned at MiniDebConfHamburg (https://wiki.debian.org/DebianEvents/de/2019/MiniDebConfHamburg#talk_schedule_v1.0.1) that there probably will be the possibility of creating Debian PPAs soon.
Watch from about 39min20s onward: http://meetings-archive.debian.net/pub/debian-meetings/2019/miniconf-hamburg/lightning_talks_demos.webm