My son bought me this cell phone holder that suctions to the windshield. The arm is firm but flexible. I use a speedometer app that shows the mph, distance, average speed, etc.....
I bought a holder similar to yours, but the arm was not strong enough to keep my iphone7 upright. I took the arm off and glued a magnet to the back. Works on my steel dash, probably not so well on your wood. There are many, many free GPS speedometer aps, pick the one with the display you like best.
This is the one I use. I think it was around $30 at Best Buy. The suction cup is almost permanently tacky, but doesn't leave a residue. If it gets dusty, I wipe it off with a damp rag and it's good as new. It'll stick to painted surfaces, glass and textured dashes. It holds my iPhone 7 just fine. A little tight if you have one of the "Plus" iPhones.
I use a similar device for my gadget. Just won't work for video. Like to see what other people are using for video.
A bicycle speedometer mounts nicely on the horn button. Under $25.
For $60 I have a bicycle GPS. Rechargeable, odometer, trip counter and speedometer about 1.5"quare. I mount it on the lower left corner of the windshield with Velcro. Fantastic, no wires easy to see/use, accurate,love it.