That's cleaner option and just work through distribution after death. There are banks, however, that won't let you set TOD ( I have one like that) or not allow multiple people on TODs. If there isn't accessible fund set aside to cover funeral and other expenses it makes it difficult to access those accounts legally in a timely manner unless he or his sister is on that account as well.

I would hire an estate lawyer / planning service but if you want to get some more info, search for Estate Planning in YouTube. America's Estate Planning Lawyers will be top choice and I watched quite a bit of his material. He covers a lot of material you need to research and work through that can't possibly be covered in this comment section.

Generally, it's not recommended to move parent's house under kids' name(s) until after death due to capital gains treatment differences when you sell the house if you received it after the death vs you as the owner. Also, other benefits your dad may be receiving can be impacted.

Definitely worthwhile to start going through all his financial accounts and help him set beneficiary ( or TOD - transfer on death/POD payable on death ) on all of them if allowed to you and your sister. I think it's easier not going to probate for checking/savings type of accounts so it maybe worthwhile to setup a joint account between you and your sister and move funds out. Retirement accounts should just have beneficiaries set and it should be a fairly easy process once you have the death certificate to get distribution without going through probate.