Do you feel ok buying 2nd hand computer hardware given the chance it could have malware put on it?

Newcad

OK so it's a Linux specific issue.

Many of the newer 4g dongles/hubs support Linux (Including some in that Amazon link, look particularly at the 'industrial' ones).
If it's more than just the Linux drivers though then "usb-modeswitch" software may be what you need.
https://www.draisberghof.de/usb_modeswitch/

However to get back to your original question - It's very unlikely that anyone has trojaned any malware onto a2nd hand dongle like that.
Yes technically it could be done, but why, what would they get out of it? It's not something that would be worth doing. (If someone wanted to do that then USB memory sticks would be a better choice to target as they could shift more of those than an obscure discontinued dongle).