Yes, you can use a USB serial device e.g. /dev/ttyUSB0 see emontx direct serial example for emonhub:
[interfacers]
### This interfacer manages the EmonTx3 ESP format serial
[[SerialTx3e]]
Type = EmonHubTx3eInterfacer
[[[init_settings]]]
com_port= /dev/ttyUSB0
com_baud = 115200
[[[runtimesettings]]]
pubchannels = ToEmonCMS,
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