Some still do, most don't these days.

Specifically those using Snapdragon, the company has a policy of some kind whereby anyone using that chip for a retro handheld can't sell those cards along with the device.

But aside from that, I can only think of one big-big company which does it now: Anbernic. TRIMUI is a smaller company which sells the ROMs on a card also, but now that these devices are such big business...most opt for discretion and don't do the cards.

Official companies anyway, I'm sure you can throw a rock and hit an R36S with a card included these days.