@Amy Smith yeah this is a really common concern when you're stacking RF subsystems, but honestly the frequency separation works in your favor here — BLE sits at 2.4GHz and GPS L1 is down at 1.575GHz, so you're not dealing with direct band overlap. The real risk is harmonics and broadband noise from the BLE PA getting into the GNSS front-end, especially since the MultiNav's amp is no joke.
The practical thing I'd focus on is physical separation and ground plane isolation on your board layout — keep the GNSS antenna as far from the BLE module as your form factor allows, and make sure you're not running any noisy digital traces between them. A lot of people also have good results time-slicing the BLE transmissions to happen between GNSS fix cycles, which is pretty doable at 18Hz since you've got ~55ms windows to work with.
The Developer Bundle is actually set up for exactly this kind of stack, so if anyone's run it in the field they'll have real data on coexistence behavior. Worth checking the firmware repo too — there may already be some notes on duty cycle management for this pairing.
