How do I verify ownership for Activation Lock removal on iPhone?

Sorry, but no. We can't help.

Unfortunately, neither can Apple unless you can meet the qualifications in this document:

How to request access to a deceased family member’s Apple Account - Apple Support

The family of the deceased can request access to their Apple account with the proper documentation, which would potentially allow you to remove the lock.

Of course even if you can unlock it, it's not going to be of much use. App developers no longer support it and it's not usable even as a basic phone in most of the world.

Sorry, but no.

Nope.

And I was answering your original question.

FelipeV was replying to your question......

Do you know if there's any other way to get the activation lock removed, even if it's just to use the iPhone 4S for something other than calls and texts

If you're located in the U.S., it's useless anyway. The 4s can only connect up to 3G, and all 3G service was shut down in the U.S. around mid 2022.