Just tried this for the first time to pay my internet bill. It worked flawlessly from the tbc app! The only thing I noticed is that the amount paid by my wallet was exactly $1 higher on a hundred. Not sure if that was an exchange difference or a charged fee. Either way worked great.
I was concerned because you have so many warnings on browser settings but I use Brave Browser by default and wasn't sure how I could turn it off for just one website without knowing the website in advance. But the tbc app seems to run its own so no trouble. I guess going through your web site that will need to be taken into consideration.