At very least some free tier for NAT64 gateways, or shared DNS64/NAT64 alike https://nat64.net/public-providers for Amazon users would be nice. I'm fine with ipv6-only connectivity for a lot of hosts, but once in a while they need to download some software / updates from github.com which is still ipv4-only. Paying fixed extra cost for every subnet just for 100MB/mo download per host is meh.