I ordered a pair of Echo Frames from Amazon... and prescription lenses specifically to fit Echo Frames via LensesRx. Note: to do the latter you'll need your prescription - numbers for the Sph, Cyl, Axis, and Add for OS and OD (your left and right eye -oculus sinister and oculus dexter), as well as your PD, or pupillary distance.
The prescription lenses are easily popped in. Next you 'add' your charged Echo Frames to 'Your Devices' in the Alexa app and off you go...
You don't get much of a choice (back, blue, tortoise versions of the basic frame) while buying the Echo frames, but it looks fine, albeit slightly on the "chunky" side.
The technical specifications:
Echo Frames Reviews:
Echo Frames YouTube Reviews: