The wisdom you seek is here:

Shimergo | CTC

Indexing bicycle drivetrains are simple machines. Despite this, only a small minority of avid cyclists (and even shop mechanics) ever really figure out the relationships between shifters (cable pull), derailleurs (mechanical advantage) and cassettes (cog spacing). If you read the CTC article, and truly understand it, then you have what you need -for life.

I am not aware of shifters that feature the ability to vary the cable pull. There are some hack solutions out there for adjusting derailleur mechanical advantage (such as the alternative cable pull trick). Or modifying the shifter cable pull. These can work fine. Most of my bikes feature a mix of derailleurs and shifters that strictly not 'manufacturer recommended'. For example, I use Campy 10-speed Ergo levers with the older generation of Campy indexing derailleurs. This allows me to run Shimano 10-speed cassettes and hubs. Cheaper and far more available than the Campy equivalents. Works perfectly every time.

Understanding indexed shifting at a deep level will allow you access these optimal solutions. And avoid endless frustration working on kludge solutions that will never be compatible.

Wisdom here comes from understanding the numbers. If you know the cable pull of the shifter, the mechanical advantage of the derailleur, and the cog spacing of the cassette, and you run the math, and it should work, then it will work. For me, this approach has never failed.

I have no respect for hack mechanics who suggest that: "perhaps you should just try a Suntour derailleur with Shimano 8-speed shifters on a 9-speed cassette and see if it works". This demonstrates that the mechanic does not have a clue what they are doing, and they are wasting everyone's time.

It all starts with accurate numbers, and then running the math.

Good luck.