Is this in line with the TOS? I thought there were restrictions on serving non-website content in the free tier, or does that not apply to the CDN if you're using R2 as an origin?
We front our distribution service with Cloudflare Workers fronting R2 fronting S3 / Lightsail Object Store (https://blog.cloudflare.com/cloudflare-r2-super-slurper/). That brought our costs down from $500 to $2 serving the same amount of traffic.