Sounds very similar to my personal setup, but mine is a 2020 12.9 in a magic keyboard that lives on my desk.
My daily work machine is a company issued Lenovo Thinkpad hooked up to 2x external monitors.
My 12.9 is my ‘take everywhere’ machine, though this has likely become superseded by my new Mini 6.
However, when at my desk, unless using the 12.9 directly for a focussed task, it is sat at an angle to my left, and to overcome any issues from twisting to input text via the magic keyboard, I have a Bluetooth keyboard (Arteck HB-192] that allows me to connect to 3x Bluetooth devices.. I have this set to Laptop > iPad > iPhone and can type to each device a second following the touch of a button to connect to the desired device.