The one click checkout has already been solved. It’s Apple Pay. Any time I see that on a retailer i always use them because of how easy it is, all payment info, shipping info, etc are prestored, and if they integrate Apple Pay directly or through their merchant processor my trust level immediately increases.
It does help increase conversion as i do abandon some carts without that and it makes me a repeat shopper of the places that integrate.
It is a solid concept the real issue is that between Fast and Bolt it looks more like the wrong founder CEOs rather than anything else. One is completely shady and the other spends way too much time on twitter and is now potentially caught misleading customers and investors.
If they had focused more on their business and moving quickly but sustainably one if these two companies would be succeeding instead of both of them looking like they have massive issues.