Are the plugs that the expansion cards plug into thunderbolt USB-C? That’s all I can think of that they are in order to have all of the ability to do what they do. If they are thunderbolt just not advertised I might be able to use the razer external GPU thing.
They are Thunderbolt-capable ports, Framework is currently undertaking certification to allow them to say they are Thunderbolt ports. Many people have successfully used eGPUs with the Framework laptop.