Create an Okta organization and a native app. Copy the issuer and client id.
TOKEN_ISSUER="https://<domain>.okta.com/oauth2/default"
CLIENT_ID="OktaClientID"
go run ./api/main.go --server [server] --provider okta --token-issuer ${TOKEN_ISSUER} --required-okta-client-id ${CLIENT_ID} --port 8081
ACCESS_TOKEN=$(go run ./pkce-cli/main.go --issuer ${TOKEN_ISSUER} --client-id ${CLIENT_ID} | jq -r ".access_token")
curl -s http://localhost:8081 | jq
curl -s -H "Authorization: Bearer ${ACCESS_TOKEN}" http://localhost:8081 | jq