edit: I was able to get something working by setting the DNS in Peer Settings and on the Client to 1.1.1.1, then tried my PiHole IP, and that works too. It was 10.253.0.1 that was not working.
root@Odin:~# rm /var/log/wg-quick.log
root@Odin:~# cat /var/log/wg-quick.log
wg-quick down wg0
[#] ip link delete dev wg0
[#] logger -t wireguard 'Tunnel WireGuard-wg0 stopped'
[#] iptables -t nat -D POSTROUTING -s 10.253.0.0/24 -o br0 -j MASQUERADE
[#] ip -4 route flush table 200
[#] ip -4 route add unreachable default table 200
[#] ip -4 route add 10.0.0.0/24 via 10.0.0.1 dev br0 table 200
wg-quick up wg0
[#] ip link add wg0 type wireguard
[#] wg setconf wg0 /dev/fd/63
[#] ip -4 address add 10.253.0.1 dev wg0
[#] ip link set mtu 1420 up dev wg0
[#] ip -4 route add 10.253.0.2/32 dev wg0
[#] logger -t wireguard 'Tunnel WireGuard-wg0 started'
[#] iptables -t nat -A POSTROUTING -s 10.253.0.0/24 -o br0 -j MASQUERADE
[#] ip -4 route flush table 200
[#] ip -4 route add default via 10.253.0.1 dev wg0 table 200
[#] ip -4 route add 10.0.0.0/24 via 10.0.0.1 dev br0 table 200