The role of Termcap in contemporary Unix-style systems is the same as it always has been: it provides a library and database allowing software to adapt to the varying capabilities of different terminals.
These terminals can be physical (connected to a serial port, typically) or virtual, provided by any one of a number of terminal emulators (the console on ...
Erm. I think here are a few misunderstandings at work.
Termcap is a descriptional database about terminal features (*1), not device configurations.
In sense of Unix terminals aren't devices, but something connected to a device. In a more general sense, Unix-devices are (*2) interfaces that can be accessed using OS measures.
It may be this basic mixup ...
This will work with the USB floppy drive you have mentioned, a Chuanganzhuo one, using Windows 10. You have to use a proper Double Density floppy disk, not a High Density one.
I tried it with a High Density floppy disk and it gave me Parameters not supported by drive.
C:\Users\J>format a: /T:80 /N:9
Insert new disk for drive A:
and press ENTER when ...