In theory, yes. In practice, no.
I would think that there are very few people attempting to use Windows or Mac as their host computer with the Librem 5. So if you want easy access to assistance then you want a Linux computer.
That only happens if the Librem 5 boots the Jumpdrive software - which has to be loaded from a host computer to the Librem 5. For this purpose the host computer connects to the Librem 5 using a USB cable. (Any USB cable should suffice as long as it has a USB-C connector at the Librem 5 end and an appropriate connector at the host end.)
However you don’t need Jumpdrive for reflashing.