I believe that you made my point.
If after you used the NANO-ISP to upload the micronucleus bootloader, then you used the NANO-ISP to upload the blink program then you wiped out the bootloader.
After burning the bootloader with the NANO-ISP, you would have had to insert your tiny85 into your USB board and then use micronucleus to burn the blink program into it.
I watched the YOUTUBE video you referenced but its in Hindi, which I don't speak nor comprehend. I followed the video along anyhow to see what he was doing. The author DID NOT use micronucleus to burn the blink program, he used the ARDUINO ISP, which would have over-written the bootloader. [so what was his point in ISP "burning" the bootloader if he was just going to wipe it out by ISP uploading the blink program over it?? ] If you followed his video to burn the bootloader AND then uploaded the blink program then its likely that your tiny85 does not contain the micronucleus bootloader because it was wiped out by the blink program. I really think this is your problem, you presume that the bootloader still exists on the tiny85, when in fact, it does not, hence your WIN10 "unknown USB device" problem.
Let me explain a bit; since there are pull-up and pull-down resistors on the USB D+ and D- pins, when your device is plugged in, WIN10 is informed that there is a new USB device attached that needs to be enumerated (find out what it is) and since there is no bootloader code to respond to the enumeration request, WIN10 determines it to be an unknown device. As shown in the screen-shot below, when I plug in my tiny85 board (like yours) without an MCU (same effect as having no bootloader code), the Linux OS detects a new device was attached (due to the pull-ups/downs on the D+ and D- pins) but since there is no MCU to report the device info during enumeration, the Linux OS attempts enumeration 4 times before giving up and failing enumeration, as reported by the Linux OS in the DMESG logging file (last line of screen-shot).
As a matter of fact, I think this is exactly what WIN10 is telling you in the message:
"Unknown USB device (Device Descriptor Request Failed)"
The device failed to enumerate.
I suspect that the reason why ZADIG doesn't offer a driver to use for the device is because WIN10 couldn't enumerate it and so there is no recognizable USB device to offer a driver for.
I don't use any any ARDUINO's to program my AVR's. I use either TL-866, USBtiny, USBasp or AVR Dragon, so I don't know if your NANO-ISP programmer can read code or just write code. If you can read the FLASH contents of the tiny85 back into a HEX file, then do so and use a text file viewer or editor to look for code starting around address 0x19C0 (see screen-shot below), which is (approximately) where the micronucleus bootloader code is stored in FLASH memory.

If there is no code (mostly FF's) at (or near) address 0x19C0 then it would confirm that the bootloader was overwritten and not available to answer the WIN10 USB enumeration requests.
[ If you don't know how to read the contents of a HEX file, which contains record types, addresses and data, then read the INTEL HEX file WIKI page. ]
If you have not yet done so, I think you should try burning the bootloader again, insert it into your USB board then try plugging in your board and see if it gets a successful enumeration as shown in the DEVICE MANAGER. If it does then try using ZADIG to see if it will offer you a selection of drivers to install.
Suggestion: If you are going to do any program development with the AVR's, I suggest you at least obtain either a USBtiny or USBasp. They are US$3 to US$10 on eBay. The USBasp is preferred because you can select your target's supply voltage (5 or 3.3). The ONLY real issue that I have with the USBasp is that it is STILL supplied with a 10-pin IDC connector, which I have not seen used since the late 90's, instead of the 6-pin IDC connector. Make yourself a 10-pin to 6-pin adapter (see pinouts below). Learn how to use the USBasp programmer and AVRDUDE, so you can easily program your AVR's outside the ARDUINO environment if you have to, AND in this case, read your code to be sure what's in your AVR is what you think is in it.
Peace and blessings,
JQ