I'll tell you from personal experience--dont let free tiers influence your tech decisions. your early lock in decisions are the most costly and you will pay dearly long after the free tiers run out
This is worth considering, especially when you can get a DO droplet for $5/month and run whatever free software you like on there on Ubuntu. That has to be as un-locked-in as it gets. You could run the same thing from a Rasb-Pi at home!
I am happy to use Netlify as a static file host as that isn't much of a lock in: I can move to S3 later, or even the DO droplet and Nginx!
Agreed. Unless you're intentionally building some low-margin business model that requires cutting these costs, you shouldn't box yourself in and ignore potential growth because of hosting costs.