Confusion on nft tables chains usage

I'm a beginner, and recently while studying firewalls, I'm having some confusion with the usage of chains on the nft tables. I would appreciate any assistance:

input_wan
output_wan
forward_wan
input
output
forward

For the following 3 scenarios, which chain in B should I write a rule to block ping?

Scenario 1:
Topology:
A(wan port: 9.1.1.1)-------internet-----------(1.1.1.1:wan port)B
A pings B

My guess: nft insert rule inet fw4 input_wan ip protocol icmp icmp type echo-request counter drop

Scenario 2:
Topology:
A(wan port: 1.1.1.2)------------------(1.1.1.1:wan port)B
A pings B

My guess: nft insert rule inet fw4 forward_wan ip protocol icmp icmp type echo-request counter drop

Scenario 3:
Topology:
PC2(3.3.3.2)-------(3.3.3.1 Lan port)A(wan port: 9.1.1.1)=========internet=========(1.1.1.1:wan port)B(Lan port: 2.2.2.1)---------(2.2.2.2)pc1

There is a wireguard connection between A and B.
PC2 pings PC1.

My attempt using input_wan didn't work, so I think it should be: nft insert rule inet fw4 forward ip protocol icmp icmp type echo-request counter drop

With all your recent threads about nftables, it would be helpful if you post your current firewall configuration.

uci export firewall
nft -t -s list ruleset