For argument's sake, I tried this wallet just now and I can confirm it's a non-custodial wallet. Coinbase specifies it as "Self-custodial".

As for your overall suggestions, I get it what you mean.
If the customers already have hotwallets like Coinbase App, Trustwallet, etc. they can just scan qr codes to send btc as payment. Although I doubt anybody who's using a hardware wallet would be insane enough to bring it to a bar to pay for his drinks.

For convenience, the business owner has to adapt to the needs of his customers. Accepting BTC as payment through various 3rd party apps.
Here's an example, I recently saw a couple (vloggers) who took a 1-day challenge wherein they can only use Bitcoin as payment in Boracay (a popular tourist destination here in the Philippines). They've paid BTC through an app called Pouch.ph. The app converts the BTC they've paid to fiat (Philippine Peso) when the store/seller recieves it. It kinda beats the purpose of Bitcoin and whole idea behind it but it's a good start.