In short: A slightly better TMC2209.
I might be wrong since I use the driver in a diffrent printer, but the drivers seem to run cooler and more silent than the already great TCM2209.
In Klipper the driver for the TMC2209 is able to drive the 2226.
I have been building a printer using the SKR-3 mainboard using Marlin and TMC2209 drivers. This combination can produce a Marlin error No TMC connection. After damaging a TMC2209 through a wiring mistake I decided to try the improved driver TMC2226. This device uses the same settings as TMC2209 in Marlin so it is a plug & play replacement. No more errors! Much quieter particularly when running in 64 micro stepping mode.
TMC2226 is much improved version of TMC2209 and runs cooler with a much improved current capacity. Making this a good choice when using larger stepper motors.