But then you're right back to the cloud billing problem, right?

That's right, auto-scaling comes with this problem, but at least you removed one extra service/point of failure.

That's assuming you trust Linode block storage as much as you trust S3.

Trust in what sense? Uptime, security, privacy? I am not sure whether I can say I trust one or another, by personally I had a good experience with VPS/dedicated server providers, more than with cloud (AWS/GCP).

Out of curiosity I tried to look up their pricing and the first thing I am greeted with when launching their price calculator is "you must allow functional cookies".

I disabled all shields for their side and still the same thing. Waste of time

I personally never used Linode and can not recommend nor talk against it, I was just pointing out that if you want scalable solutions AWS is not the only answer.