FWIW, I placed my early bet on pipenv, but it had some significant bugs and development had stagnated (seems like it might be picking up again).

When we decided to move away, I looked at Poetry and pip-tools. Poetry seemed too different to me, don't remember specifics, but felt like too much would need to change. All I wanted was the ability to lock package versions.

Enter pip-tools. It was really simple, felt familiar, and just worked. So, that's what we chose and it's what we use to this day.