On the general subject, I use my phone and a Garmin Nuvi for nav on my bike.
In fact, used both simutaneously on the trip to/from the Reunion Camp earlier this year.
Had them both set for the same destination, and to avoid highways. It was fun to intentionally take a wrong turn, or favor one route over the other.
The routes were different, got to see lots of non-slab countryside.
For attachment, I use RAM mounts for the base connection.
Specific for my phone, I use Slip Grip Mounts.
They are tough and affordable.
They can be ordered custom, like when my phone was a Casio Commando with a double battery
, had it to me in 4 days.
My first few could release the phone if swung very violently.
A few minutes with a blow drier to increase the bend of the thumb tab and they became enduro trail rated, literally.https://www.slipgripcarmounts.com/
A Garmin Nuvi on a bike? Yes, and it has survived real soaker rainstorms without any protection or failure. I use a carrier frame specific to it made by RAM.
7 inch screen so the picture is big. I most often use it for the picture in View Map mode, while using the bluetooth on the phone app for nav directions.
I also use US Topo Maps Pro to record routes on the fly.
Gotta remember to use that more often, would have been nice to record the 3 State route from this year!