I use a K-Edge mount for the front. GPS on top/GoPro on the bottom.
The Fly6 mounts with a velcro strap, and just wraps around the post.
I'm on the road right now, without the bikes, thus, no pics. Sorry.
They make weighted bags with mounts for this purpose. https://www.amazon.com/Bestand-Dashboard-Portable-Friction-Garmin/dp/B01N6KWHSC
3m molding tape worked great. It can be removed but it's a real pain. I have a 2002 Ram 1500 which doesn't have all the modern electronic integrations so I added them over the year. I mounted a 10 disc CD changer controller to the dash bezel using 3m tape. It was there for 10 year until I removed it. I wanted Bluetooth so I found a bluetooth module that had a controller that I mounted with 3m tape. It was there for almost 10 years before I removed it. No TPMS back then so I bought a TPMS device that I mounted on the dash bezel using the same 3m tape. It's been there for 4 years now.
Your other option is to figure out how to run a bracket behind one of the dash panels and 3m tape it to that. For example, I added a carputer to my truck and needed to mount the monitor somehow but still have access to the radio and hvac controls. I popped off the dash bezel and used 22 gauge sheet steel that I screwed to the mounting screws behind the dash bezel. The steel came out where the bezel met another piece of the dash and I welded it to tubular steel to which the monitor was mounted and it could be slid up and down the tubular steel. Probably more than what you were looking for but it worked great.
You get something that clamps a RAM-mount 1" ball to.. probably the handlebars?
Then you get an extension piece and one of these, or similar: https://www.amazon.co.uk/RAM-B-132B-Drink-Cup-Holder-Ball/dp/B00CNOEA5C
This is the one I got for my grail: Dymoece Out Front Bike Computer Combo Mount for Garmin Edge 130 200 500 510 520 800 810 820 1000 1030 Touring https://www.amazon.com/dp/B07JG7CBX5/ref=cm_sw_r_cp_api_glt_fabc_ARJ8WCD2D4ZETCY3ZBNG?_encoding=UTF8&psc=1
I ordered the regular size X-grip phone holder with ball (I use a Galaxy S20 Ultra) and this to screw to the Pro Clip.
I used the Scosche vent mount clip and am pretty happy with it. I use the left side vent to mount, just my preference. You can find it here https://www.amazon.com/dp/B08F2VRQGN?ref=ppx_pop_mob_ap_share
The $100 coupon isn’t displaying anymore. But, this is the exact kit you can get off Abstract Ocean (known for their Tesla parts). They have a discount code “TESLAINVENTORY” to make it like $221~. Either or, you’re good. I wanted it faster with Amazon and the coupon was a no brainer at the time.
Amazon.ca grossly inflates the price on many items, especially from third party sellers. Abdulis uses this: https://www.amazon.ca/dp/B00AN3UUP4/?coliid=I12UZX09JPDA6O&colid=31MR4BXF6PTV8&psc=1&ref_=lv_ov_lig_dp_it
Just the remember the good old 12v power outlets, are literally just two wires and a round hole. Pretty easy to move, reroute, or add.
Or, get one of these guys, and slap it under the dash somewhere actually useful.