How to do this wireguard firewall setup in nftables in nixos fashion?

Help
1

I am a firewall newbie learning nftables and doing a similar setup in the 1st scenario in this tutorial (Site Gateway as a Spoke) .
But in the tutorial about Host β it involves PreUp and PostDown iptables script.

# /etc/wireguard/wg0.conf

# local settings for Host β
[Interface]
PrivateKey = ABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBFA=
Address = 10.0.0.2/32
ListenPort = 51822

# IP forwarding
PreUp = sysctl -w net.ipv4.ip_forward=1
# IP masquerading
PreUp = iptables -t mangle -A PREROUTING -i wg0 -j MARK --set-mark 0x30
PreUp = iptables -t nat -A POSTROUTING ! -o wg0 -m mark --mark 0x30 -j MASQUERADE
PostDown = iptables -t mangle -D PREROUTING -i wg0 -j MARK --set-mark 0x30
PostDown = iptables -t nat -D POSTROUTING ! -o wg0 -m mark --mark 0x30 -j MASQUERADE

# remote settings for Host C
[Peer]
PublicKey = jUd41n3XYa3yXBzyBvWqlLhYgRef5RiBD7jwo70U+Rw=
Endpoint = 192.0.2.3:51823
AllowedIPs = 10.0.0.0/24
PersistentKeepalive = 25

How should I implement the same thing with nftables in the nix way? Thanks!

2 
table inet nat {
    chain postrouting {
        type nat hook postrouting priority 100; policy accept;
        iifname $wg_iface oifname $pub_iface masquerade
    }
}