My motherboard has 3 nvme bays.
If I saw the need, there are cheap pcie to nvme cards, since (non-sata) nvme is just directing pcie lanes to the ssd anyway.

But like I said below, I don't even have the need to get a single ssd at the currently maximum price-effective size of 4TB, no less two or three.
In my observation putting mass storage into your pc is dying in favor of either not needing that much storage, or putting it in a nas or other internet-accessible device.

Even my non-IT friends do things like put their hdd in a usb enclosure and attach it to their (internet accessible) router.