Done and sorry 
In the spirit of the original subject, hopefully the below will be of use to anyone new to nft and trying to do a bit of troubleshooting...
- nft list tables This ones is pretty self explanatory and most people will only have table inet fw4, unless rules have also been added via iptables-nft
- nft list table inet fw4 Lists everything in a given table
- nft list ruleset Similar to the above, but lists everything
- nft list chain inet fw4 dstnat_wan Lists the contents of a specific chain within the table
It's not quite as obvious as iptables, at least to me, but a lot of chains have counters which show packets/bytes matched, but only if they've been added with a counter. Logging also works, at least on the WAN side, by adding option log '0' to the wan zone in the firewall config file, which might help anyone trying to debug issues
Finally
- nft add rule inet fw4 input udp dport 53 counter accept Adds a rule, however it's appended to the end of the chain
- nft add rule inet fw4 input position 10 udp dport 53 counter accept Adds the same rule, but after the the one in position 10 (Adding -a to the list commands gives you the handle/position)
- nft delete rule inet fw4 input handle 108 Delete a rule with the given handle, which seems to be the only way to delete a rule via nft