A relatively easy one is losing the potentiometer and circuit board of the middle motor and soldering the motor to the receivers built in ESC (if it has one, as the DelTang have). Obviously you lose the ability to reverse it, so you definitely to trim a little heavy. On the other hand you gain a lot in proportional control, compared to the servo circuit. You can also use it for the forward propulsion, sacrificing the backwards function. I would recommend the latter in larger rooms as in that case coming back down is probably more important than reversing.
If you’re up to some tiny soldering you can replace the potentiometers with two tiny (1/10 Watt) 4,7 kOhm resistors.
You can consider to replace the connectors by soldering directly to the receiver, but to be able to use a 9” balloon as I believe the Plantraco Nanoblimp does, one needs to bring it all below 6g. That will need another approach and another Ible. (If you’re interested, subscribe to me).