...every time I read a post like this: I remind myself to strap the battery into my Mavic 2's... better safe than sorry. Zip tie, or velcro strap: it'll keep the battery connected.
A "smart controller" for the gen #1 Mavic Pro? No such animal. That type of integrated controller only started with the Mavic 2 series (RM500) which is not compatible with the original Mavic Pro.
It won't make that much difference if, as per your original description, you fly low level with solid objects sporadically blocking the signal. The problem isn't signal strength, it's attenuation.
Like I said: small gains? Perhaps... but don't...