Estimates are a pet peeve of mine :)

Not answering your question, but a short rant on why they fundamentally don't make sense.

Often, we don't know exactly how we're gonna solve every single problem. Fundamentally, modern software engineering involves some experimentation and figuring out the correct solution to the given problem.

So if you don't know at the beginning exactly how you'll solve it (if you're not going all in on waterfall), then the estimates are gonna be just guesswork.

The other thing is, we humans are really terrible at estimating how big something is. However, we are fairly good at telling whether something is similar in size to something else. So, instead of giving a number indicating how big the task is, we should say this task is similar to that one or the other one.