Hello,
I don´t know if you read this post already - REACH M+ and DJI MAVIC 2 PRO integration for RTK /PPK precision survey
We search for the same easy affordable solution - but it seems we have to manipulate the drones ourselves (at least for me this is no option because of security reasons) 
or we have to pay someone who did it already for us and knows what he does - and gives us hopefully some kind of warranty 
Best regards!
Steffen