Using a G-Code RTI system you can move a holster from MOLLE attachment points, to drop-leg platforms, to belt, paddle, and duty drops.

RTI works with Safariland, G-Code, Bladetech, Serpa, and several custom holster makers.

RTI Hardware

Decide what holster you want, then use RTI hardware.

ETA: I use RTI hangers to swap out multiple Safariland and G-Code holsters for different handguns onto a duty-drop on a MOLLE belt.

It's all pretty simple:

1.Pick a holster. When looking at retention there are different types.
-Safariland has different options. Some use the thumb to release the gun either via a simple thumb button or via a thumb activated hood. Some use both.
-G Codes use either a friction lock or a thumb activated spring loaded hood.
-Blade-tech also uses friction fit, thumb break, or a spring-loaded thumb-activated hood.
-Serpa use a single trigger finger release. I won't go into it, but you can read WHY I/others strongly recommend against Serpas.
-There are also custom makers that will make whatever holster you want and integrate RTI into the design and have a variety of retention options. Vigilance Tactical, Fury, Off the Grid, T-Rex Arms, and KT Mech.

My favorite is the Safariland with the single thumb release. It's the fastest (release and reholster), and comparatively safest retention design.

2. Buy the correct RTI "Hanger". You remove all the hardware from the holster backing and replace it with the hanger.
From the acessories page
Hanger:

This particular hanger is the Universal variation one for Safariland and Serpa.

3. The RTI hanger locks into the RTI wheel.


This wheel can be found on several mounting options
Paddle
Belt Slide
Duty Belt Drop
Molle Belt Adapckter
MOLLE Adapter
MOLLE Claw
Drop Leg

There are other multi-platform adapters made by Safariland and Blackhawk but they only work with those brands holsters. The RTI is by far the most universal.