GPG error with Ubuntu Server 20.04

#1

sudo apt update gives me:

W: GPG error: http://apt.radxa.com/focal-stable focal InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 9B98116C9AA302C7
E: The repository ‘http://apt.radxa.com/focal-stable focal InRelease’ is not signed.

I know I can solve this by deb [trusted=yes]

But shouldn’t public key be made available?

Many Greetings and this is my first post
John

#2

Ok I needed to do:
wget -O - apt.radxa.com/focal-stable/public.key | sudo apt-key add -

from https://wiki.radxa.com/Rock5/linux/radxa-apt#focal-stable