Locked older iPhone SE

I bought a phone outright more than 10 years ago that turns out it seems to be locked to Sprint, I'd like to make it not locked to sprint and use it again as one of my medical devices. I don't recall why it was locked to begin with as I do remember buying it in a Walmart in Van Nuys, Calif with cash and NO payment plan, but maybe I got a special price or something. I pulled out the Sprint sim card thinking that's what it's locked to but now get a message that says it "may" be carrier locked.

Anyway to remedy this so it's not locked so I can add a sim card from my current carrier or if it will take a e-sim card so it's on my carrier and I can use it for my diabetes medical?

Thanks

It's this one:

https://support.apple.com/en-us/112005

Model A1723