How to use 2 USB C external drives at full speed when I only have one free USB C port?

I have 2 USB C external SSDs and a 2020 M1 Mac Mini which has only one free USB C (/thunderbolt) port. They have an approx. 800mb/s speed through the USB C port but only have a 340mb/s speed when I plug them through my hub or on a free USB 3 port with an USB 3 adapter. I tried different hubs or adapter and couldn't get better results. What hub or adapter could run them both at full speed?

Thanks