How to set up IPV6 NAT using nftables?

Since the master has switched to fw4, iptables becomes legacy, but I can't find a way to use nftables to set up IPV6 NAT. I have kmod-nft-nat6 installed.

The command doesn't work:

nft add rule ip6 nat POSTROUTING ip6 saddr $(uci get network.globals.ula_prefix) meta oif wan counter masquerade

masq6 maybe, but I dont know if it was updated