Proper estate planning (Trust, will, healthcare directive, etc.) are all important, but even with a good plan in place, there are a few not obvious things that were a surprise to me:

• Banks will disable online access the moment they get a death certificate, and from there, the process is entirely opaque. If you have passwords and access, knowing account numbers and balances before you notify the bank of the death can be a big help.
• Email accounts like gmail are often the center of people's business life, and having access to them can be a massive help. But Google will not help you get access to a decedent's accounts if you didn't set it up in advance. Even if you know the person's password or access codes, Google makes it very hard to access a person't account without their phone. They offer inactive account access to automatically grant access after a period of time. It's not great, but might still help.
• There's a high probability they have accounts, insurance policies, benefits and liabilities you don't know about. This can be a chore to figure out in retrospect.

I don't think there's a perfect solution, but after going through this with my parents (who did have a trust, will, advanced directives, etc.), I decided to make a "What do do if die" document for my kids. It's a few pages long, details accounts, what stuff I own, what I still owe, and tells them how to get and use passwords and 2FA seeds. Maybe most important, it tells them who they can call for help for certain things. We also did a trial run. Made me realize that so much of life is tied to my phone for shitty 2FA and identity tracking. Once I realized the instructions were "If my phone dies with me, you can't do any of this" it made me try to find solutions that were secure, but not in the hands of big tech and telco companies.