Let me tell you what happened in my Dad's world.
Mom passed away in April 2024. She handled everything. The really fun part was that she kept everything in her brain... didn't write anything down, except she wrote physical checks written in her checkbook, but without a running balance. Dad was a mess, wondering what he would do. I took over for him. It took about 2 months to complete the forensic audit of their books. I built a spreadsheet to track his expenses. He has access to his online banking and he can have the spreadsheet whenever he wants it.
He has seemingly forgotten everything he ever learned about computers and software since Mom isn't there as a safety net, so he has only asked for it once. He does go into his Internet Banking and email but not much else.
So, my point is that he will find someone, a child, family member or friend to help him sort out anything left to him... or, he will figure it out himself. You don't have to worry about it. Leave him with better records than my Mom left my Dad. It'll all work out.