What does this even mean?

but I do believe you will have to have a connection in order to play cause it’s made in the Unreal Engine, it’s using cross-progression, crossplay, I do believe we need you to be online," said Listo.

I've been using Unreal Engine 4 since 2014 and in 2020 started using EOS which I've shipped on a game. This is bullshit. It's entirely bullshit that you don't need someone 10 years into the games industry with the relevant engine experience and relevant online subsystem experience to tell you it's bullshit. You already know it's bullshit. But here is a random expert opinion to definitively confirm it's bullshit.

The only thing they had to do is make it so you can store your progress locally until you connect to a server. I do that with my achievement system in an indie game I made for under 10,000 USD from my publisher. It's insane to think this is their excuse.

Believe

...you can play it with bots? That's kind of how any 4 player co-op game works lol. I don't remember Left 4 Dead 2 being online only when I wanted to play by myself. Payday 2 already has a whole community of people who play the game by themselves. In fact I believe you can even disable the bots and do the whole maps solo.

You can play with 3 AI heisters, or you can go in solo.

Source: I spent a lot of time figuring out routing for solo stealth heists back when PD2 was more popular.