It’s totally fine if plans change and you decide not to move forward with a candidate, but I think a short email isn’t too much to ask after spending multiple hours on the various interviews.
That said, the interview process was otherwise pretty good and the work you’re doing sounds really interesting, so I would still encourage others to apply. Best of luck with Formal!
Who are your customers?
> we’re rethinking serverless from scratch:
What are the use cases that you target?