SD Card Speed = 90MB/s Easily - PS4+XBOX1 Were using Slow Laptop 5400RPM 70MB/s~ most of your library (99.9%) will run just fine on Steam Deck (Just slower loading) the 399$ Model
HUAWEI 128G NM Card Memory Card 90MB/s Smart Flash Card 64G 256G Nano Memory Card for Mate 20 Pro Mate 20 X P30 | Alexnld.com
Dodd Camera - SANDISK 64gb Extreme Pro SDXC UHS1 170MB/s read; 90MB/s write Cl10 U3
SanDisk 512GB EXTREME PRO SD 170/90MB/S RW C10 UHS U3 V 619659170370 | eBay
9309 90-MB Yanmar Transmission / Gear Cooler
Used SanDisk Extreme Plus 32GB SDHC 90MB/s Card | MPB
SanDisk Extreme Pro Micro SD Card 64GB UHS-I SDHC Class 10 170mb/s and – JG Superstore