They are a bit pricey

Huawei’s proprietary Nano-Memory (NM) cards have unofficially arrived in the Philippines. Reseller XUNDD Philippines is selling them in both 128GB and 256GB variants. They also have the card reader for sale should you need to use these proprietary cards with your computers. Only the Mate 20, Mate 20 Pro, and Mate 20 X support this memory card, which is approximately the size of a nanoSIM.

As of this writing, the seller has sold a few NM cards already.

https://www.facebook.com/xunddphilippines/posts/271313556922412

Priced at Php 3,200 and Php 6,200, both the 128GB and 256GB cards are pricey. For reference, you can get a 128GB Sandisk Extreme MicroSD card for Php 1,499, while the 256GB Sandisk Ultra MicroSD card will cost you Php 3,699. Both cards have the same read and write speeds of Huawei’s NM cards. While they are expensive, these memory cards are your only option if you want to expand your Mate 20 and Mate 20 Pro’s internal storage.

While Huawei wants these NM cards to replace MicroSD cards in the future, it has to convince OEMs to invest in this new memory card format.