You can try to replace this:
ExecStart=/usr/bin/bash -c "if (nft create chain ip qubes waydroid-input) &>/dev/null; then nft add rule ip qubes custom-input jump waydroid-input; fi"
ExecStart=/usr/bin/bash -c "if (nft create chain ip qubes waydroid-forward) &>/dev/null; then nft add rule ip qubes custom-forward jump waydroid-forward; fi"
ExecStart=/usr/sbin/nft add rule ip qubes waydroid-input iifname "waydroid0" meta l4proto {tcp, udp} th dport { 53, 67 } accept
ExecStart=/usr/sbin/nft add rule ip qubes waydroid-forward iifname "waydroid0" oifgroup 1 accept
ExecStart=/usr/sbin/nft add rule ip qubes waydroid-forward oifname "waydroid0" iifgroup 1 accept
ExecStop=/usr/sbin/nft flush chain ip qubes waydroid-input
ExecStop=/usr/sbin/nft flush chain ip qubes waydroid-forward
with this:
ExecStart=/usr/sbin/iptables -I INPUT -i waydroid0 -p tcp -m multiport --dports 53,67 -j ACCEPT
ExecStart=/usr/sbin/iptables -I INPUT -i waydroid0 -p udp -m multiport --dports 53,67 -j ACCEPT
ExecStart=/usr/sbin/iptables -I FORWARD 2 -o eth0 -i waydroid0 -j ACCEPT
ExecStart=/usr/sbin/iptables -I FORWARD 2 -i eth0 -o waydroid0 -j ACCEPT
ExecStop=/usr/sbin/iptables -D INPUT -i waydroid0 -p tcp -m multiport --dports 53,67 -j ACCEPT
ExecStop=/usr/sbin/iptables -D INPUT -i waydroid0 -p udp -m multiport --dports 53,67 -j ACCEPT
ExecStop=/usr/sbin/iptables -D FORWARD -o eth0 -i waydroid0 -j ACCEPT
ExecStop=/usr/sbin/iptables -D FORWARD -i eth0 -o waydroid0 -j ACCEPT
untested