For near field listening, where you can easily reach for the PecanPi volume knob, it should be a nice combo.
For mid/far field listening, since there’s no remote control for PecanPi and of course no volume control for Navis, I would avoid relying purely on software volume control… While it can work, it can also be disastrous.
Unless of course you don’t mind getting up to change track volume when needed. Or you can set a reasonable volume with the PecanPi volume knob while using Roon’s auto volume levelling, to keep a more stable volume between tracks/albums. So this is more a combination of knob volume control and software volume control, and a bit safer that turning the volume knob all the way up and using 100% software volume control.
My only point is to be careful, since Navis has no volume control. I saw a forum where one guy bought Navis and a DAC, set it up at home. And only then realised he had no way to do hardware volume control…