Consider storing the data on Backblaze B2 ($0.005/GB/month) and serving content via Cloudflare (egress from B2 to Cloudflare is free through their Bandwidth Alliance).
(No affiliation with either; just a happy customer for a tiny personal project)
(No affiliation with either; just a happy customer for a tiny personal project)
https://blog.cloudflare.com/updated-tos/
The prohibition on non-HTML content seems to only apply to CDN usage now.