Searching for a modern notebook (~2020-2021) with two WLAN internal slots on the board. The one card to receive corporate VPN from the router and the second for Internet. My current Dell E6530 fits the requirements, but a bit old - it's from 2013.

You have mzny options for dual wlan network interface you can choose any one from below links, especially they are designed for linux.

These days, dual waln slots are difficult to find in modern hardware, Still I was able to find those in Tuxuedo computers. The laptops or notebook I found doesn't have two waln slots.But they provide optional wifi support too*. Using which you can have dual wlan network almost suites your needs.

For VPN connect using RJ45 lan port
Connect to internet using wifi, If not possible go with RJ45 to USB Adapter which is tiny and easy to connect using USB.
1. TUXEDO Aura 15
2. TUXEDO Aura 15 - Gen2

I can't list all of them one by one you can explore yourself ...
Laptop series continued

Goodluck in advance  ;D

Check out this note book too, you can connect multiple wlan ports to anywhere really the best architectured notebook I found
1. Framework Notebook
2. Ethernet Expansion slot

This one can upgraded in future and the hardware is almost open source.