How can I locate unused drivers (kext files) on my mac which I see exist using kextstat command?
You can search for the bundle id with kextfind.

kextfind -case-insensitive -bundle-id -substring 'com.iospirit.' -print


The above should print a list of the kernel extensions (kexts) you've mentioned, including their paths.

Usually kexts are found in...
/System/Library/Extensions/
/Library/Extensions/
...or within Application packages and /Library/Application Support/.

There is also StagedExtensions, since the introduction of "User-Approved Kernel Extension Loading", where they can also be found in e.g.
/Library/StagedExtensions/Library/Extensions/

StackOverflow has a relevant question and answers about "StagedExtensions", including removal here:
https://stackoverflow.com/questions/46535279/what-is-library-stagedextensions-for-and-how-to-remove-extensions

For more information on user-approved extension loading and their locations (mentioned above) see also this archived Tech Note from Apple about "User-Approved Kernel Extension Loading"