I don’t think this is emphasized enough - you’re moving from the conventional
to the serverless
i.e. the frontend has to be more than just a UI.
If you’re using serverless for cost savings you’re missing a big trick
Mike Roberts of Symphonia (“free” ebook)
His 2016-Aug-04 article on martinfowler.com
While it’s not under the umbrella of serverless, there are other potentially on-the-cheap compute options like bidding for unused capacity.