When your router’s chips are made in China, flashed in China with closed source firmware and the money you pay goes to Chinese companies, then it’s backdoored.
When your router’s chips are made in China, flashed in China with closed source firmware and the money you pay goes to American companies, it’s bulletproof.
Just open your “secure” “American” router and look where they are made and flashed. I bet it’s not USA.
Personally, i have never experienced problems while reading from USB sticks, but i have while writing. I have a 15+ years old USB2 stick and a new USB3.x stick. The USB2 stick writes with constant ~20MB/s, while USB3 is all over the place between 200MB/s and ~0.1MB/s. Unusable for me. For a while i used external HDDs and SSDs over USB3, as they somehow run without problems, but they are cumbersome and expensive.
Therefore i have switched to transfer files over the network (for large files i plug in Ethernet) using KDE connect. Unfortunately it can not send folders (yet), so i would .tar them before sending, and untar them after.
LocalSend would also be an option. Maybe that can do folders natively.