Windows BLE Compatibilty

I made a BLE peripheral (nRF52 + SDK11.0.0 + s132) and have so far been using Android devices (that supports 7.5ms connection events) to connect to it. I want to connect to a PC now and support various Windows operating systems.

I am a little confused on how these dongles interface with the PC. Do they use the BLE APIs or do they use the CDC/HID APIs (so that almost any Windows OS can communicate via CDC/HID and the API does the translation to the BLE interface)? If the prior, then Windows XP/7 wouldn't support the dongle, correct? But an app written in C# would use Window's BLE API to communicate with the dongle, correct? If the latter, an app written in C# would simply use HID/CDC send commands to the dongle to control the BLE (and have it connect to the peripheral and read/write etc), correct?

The peripheral can stream data over notifications using 7.5ms connection events (which works great with some Android devices). Are there any BLE dongles that support 7.5ms connection events and use HID? Or am I better off creating a central with the desired USB-HID interface (i.e., a nRF52 + separate USB MCU or using the new nRF52840)? To be clear, I will supply this PC dongle to my customers (or they can buy it if off-the-shelf) but it cannot be something bulky like the nRF52-DK.