Yes, they are almost certainly sending the emergency messages as cell broadcast messages.
This is a feature that was present from the early days of 2G GSM networks, with widespread support in phones from the pre-smartphone era, provided you can find out what channel numbers you need to subscribe to in order to receive local emergency messages. More modern phones take away the need to manually subscribe to emergency alerts, and probably add some extra features on top, but I believe it’s the same basic feature. Caveat: my country never sends cell broadcast messages, so I have no first-hand experience of this actually working in practice.
Unfortunately cell broadcast messages are not something the Librem 5 currently supports. So, if you need a way to get access to the messages right now, I would think your best option is to pick them up on an old phone. Some phones might even pick up the messages without a SIM, if you’re lucky.
You might find that the Samsung A50 lets you configure subscription to emergency messages and/or to specific cell broadcast channels. I have no experience with the A50, but this would be the logical thing. It would be worth having a look in the settings to make sure.
It looks like Librem5 cell broadcast message support is on the cards. But more work is required to make it happen, which means that if it gets implemented it might be too late to be of any help in the current emergency.
I also found a discussion about emergency alerts in Mobian, which is relevant because PureOS and Mobian share quite a few software components.
Sorry that this isn’t much help. I hope you manage to keep out of danger.