Finally got the cheapest USB 3.0 Express Card for my T420 😁 : r/thinkpad
ExpressAdapt PCMCIA PC CardBus to USB Mode ExpressCard Adapter, Synchrotech
Amazon.com: StarTech.com PCIe USB 3.1 Card - 2x USB C 3.2 Gen 2 (10Gbps) - PCIe Gen 3 x4 - ASM3142 Chipset - USB Type C PCI Express Card (PEXUSB312C3) : Electronics
Amazon.com: StarTech.com 2 Port Flush Mount ExpressCard 54mm SuperSpeed USB 3.0 Card Adapter with UASP - Dual Port Laptop ExpressCard USB 3 Controller (ECUSB3S254F) : Electronics
Amazon.com: StarTech.com 2 Port ExpressCard SuperSpeed USB 3.0 Card Adapter with UASP - USB 3.0 Controller - USB 3.0 ExpressCard - USB 3.0 Adapter (ECUSB3S22) : Electronics
USB to ExpressCard
Flush Mount ExpressCard 54mm USB 3 Card - USB 3.0 Cards | StarTech.com