I tried also with ip address with same result
This is my export
/interface wireguard
add listen-port=51820 mtu=1420 name=wireguard1
/interface wireguard peers
add allowed-address=0.0.0.0/0 endpoint-address=85.178.50.8 endpoint-port=51820 interface=wireguard1 persistent-keepalive=30s public-key=\
"key="
Hi, It sort of seems reasonable,
Some thoughts,
Do you have a static routing entry or rule to route things to the wireguard interface.
Disable that for a while.
In winbox, wireguard / peers, open the peer.
When you enable wireguard, do you get both TX and RX.
If not Stop and fix this, (it's pretty much destination IP address, Port and Public/Private keys, perhaps some route thing).
Do you have an ip address on your wireguard interface. (And also at the raspberry pi end)
Strictly you probably don't need one, but it likely makes fault finding a bit easier.
eg.
/ip address
add address=192.168.98.10/24 interface=wireguard1 network=192.168.98.0
Then in your peer setting change it to: allowed-address=192.168.98.0/24,0.0.0.0/0
(Presumably the raspberry pi might have allowed-address=192.168.98.10,someOtherRange for this peer)
Then ping the raspberry pi (wireguard ip address) from the Router.
If you get that working, the rest is probably ordinary routing issues.
If you have a static routing entry (above), try turning it on again,
do you still get tx/rx, can you still ping the raspberry pi address from the router.