Google Knocker-up: a new Assistant feature that wakes you up with a gentle voice and interacts with you as you get out of your sleepy state.
Might be worth a rebranding, though.
A bit of Googling has found several chat apps (e.g. Holla, Wakie) but none that specifically mention an alarm feature, but I'm sure I remember it.
It has obvious potential for trolling and abuse, but maybe a premium version, where you pay a small fee for the best 'knocker-ups' could be popular!
Here’s an article from 2014: https://techcrunch.com/2014/12/10/wakie/
I guess it's one of those ideas that seems fun but has way too much potential for creepiness!