That won't work if you need to access IPv6-only services (as the Czech government will make theirs). In other cases it may "work" but perform worse than IPv6.

Why the desire for a NAT? It's technically possible on IPv6 too (NAT66), but SLAAC dynamic addresses + a non-NAT firewall + possibly ULA are generally a better way to get the combination of privacy + security + local addressing I think most people associate with NAT in IPv4.