NetworkManager with version 1.26.2 and higher supports WireGuard in the GUI.
Choose Import a saved VPN configuration...
Press the Create... button and select the WireGuard configuration file you downloaded from IPFire.
This will automatically import all the required WireGuard parameters and you will then be shown a Profile entry like the following
Initially the Connection name will be set to the same as the Interface name but you can change the Connection name to whatever you want, as shown above.
Press the Save button to save the connection profile and the Network Connections page will then show the saved entry.
The WireGuard VPN Tunnel will now be listed in VPN Connections list from the Network Manager icon in the Task Bar.