Yes Howard , guacamole works for it's use case, just like Plan9.
In your case you might even be better off using Google Chromeboxes and have everyone connect to a special server for what is needed using Google's project for work. It's called G suite and it is free to try.
More information is available here.
Or you could try testing guacamole using AWS and LDAP from Gsuite,
Using IPP to print , and connect to a Plan9 or other Linux instance for nfs services.
If you want to store information elsewhere.
You possibly may be needing to use some type of ERP or accounting package like postbooks or something like that.
However Plan9 probably would be something that will not work for your muggles.
However most people are comfortable using Google suite or Microsoft Suite right?
Here is a comparison of what they offer.
It also has a large marketplace of partners as well. Blackbaud, Dynamics, Zoho, WebEx, and a lot of other partners are also available in the g suite marketplace too.
As well as Chrome for Enterprises which allows anyone with a chrome device login to the Google suite network applications with their credentials.
You can also use POS systems like clover or others that are available from firms like FirstData.
You can also use other service providers for payroll , time clock, and so forth like Sage, Sap, Epicor, Netsuite , Rippling, Paychex, Workday, ADP , Xero, and others.
Note using the cloud
it makes things easier =]
It also depends on what you want or need to do.
All you could need is something a la LTSp
However I think thin station like is going to be a better bet if you all ready have thin clients around. And you are already using RDP. Versus PCoIP.
More information about Plan9 is available at this site wiki.
Here is a cool design for a small Raspberry Pi Plan9 Cluster for research and development.
Hopefully this will help out.
You may just need to copy data using "DD" to a new disk.
Then you can start over with the latest operating system you want to use.
I recommend using Debian, or RedHat with your favorite GUI, KDe, XFCE, gnome or others.
If you use others your mileage may vary.
We use RedHat and pay for it, along with IBM, and others. We also use AWS, Microsoft, and a lot of other stuff.
Anyway if Centos Linux s not working.
You may want to try using Centos Stream which is a bit behind Fedora.
Let me know if you need more information or assistance.
Warm regards,
Justin