There were still a couple of services/features that choked on IPv6 last time I looked (1.5-2 years ago) but it works with most things and they do seem to be making progress on the others.

I don’t know any software that doesn’t work with IPv6 as of 2021.

Just some internet services that haven’t upgraded. (But fixed by NAT.)

There's a matrix provided by Amazon themselves listing the level of IPv6 support in their various services: https://docs.aws.amazon.com/vpc/latest/userguide/aws-ipv6-su...