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Using the correct command:

halcmd: loadusr -Wn vfd hy_vfd -d /dev/ttyUSB1 -b 8 -p none -s1 -r 9600 -n vfd

worked.

Just having someone to bounce ideas off helps immensely.
Thank you Hakan

dmesg | grep ch341
[57931.173236] usbcore: registered new interface driver ch341
[57931.173797] usbserial: USB Serial support registered for ch341-uart
[57931.173820] ch341 7-1:1.0: ch341-uart converter detected
[57931.189484] usb 7-1: ch341-uart converter now attached to ttyUSB1

alcmd: loadrt -Wn vfd hy_vfd -d /dev/ttyUSB1 -b 8 -p none -s 1 -r 9600 -n vfd
Note: Using POSIX realtime
-Wn: dlopen: /usr/lib/linuxcnc/modules/-Wn.so: cannot open shared object file: No such file or directory
<stdin>:1: waitpid failed /usr/bin/rtapi_app -Wn
<stdin>:1: /usr/bin/rtapi_app exited without becoming ready
<stdin>:1: insmod for -Wn failed, returned -1
halcmd: quit
Note: Using POSIX realtime

Nope:

lsmod | grep ch341:

ch341 28672 0
usbserial 65536 2 cp210x,ch341
usbcore 348160 9 usbserial,ehci_pci,usbhid,cp210x,mt76_usb,ehci_hcd,ch341,uhci_hcd,mt7921u

looks like both have been loaded properly.