Making Apple Pay more accessible for elderly iPhone user

Question to help an elderly iPhone user - how can they use ApplePay if they’re not able to double click the lock button to prompt the wallet and then again choose the card they would like to pay with?

I’m trying to make ApplePay more accessible for my father who is on iPhone user but due to a condition is unable to double click the side button for ApplePay & to choose the card.

He has accessibility touch active and can click into ApplePay from the home button but he still runs into trouble actually using a card due to the double click feature.

[Re-Titled by Moderator]