There is a 3 pin diagnostic plug to the right of the steering column.
The 800 has a Delphi MT05 ECU which is not OBD2 compliant.

Have a look at this site: https://netcult.ch/elmue/HUD%20ECU%20Hacker/
You will find answers to all your questions.

I have used his application numerous times to clear codes, remove speed limiters, etc on my 800EX

Check atelierdano.com

Twice the size for about the same price as the CFMoto one.
I just put one on a few weeks ago and really love it.

How were you able to make changes to the rev limiter and top speed? Any screen shots would be great

You just need to modify the 4 values highlighted in the attached screenshot.

Already have full access to the ECU.
I removed the speed limiters and bumped up the max RPM a bit.
Just no experience with tuning the airflow, the curves, etc.

Software was identified in the original post. It can read and write the ECU.

It can be downloaded here: https://netcult.ch/elmue/HUD%20ECU%20Hacker/
As for the required cabled, I am using a J2534 tool, mainly used in the automotive industry. And a homemade cable to interface between the Zforce and the J2534.
Documented here: https://cfmoto-forum.com/800ex800/efi-diagnostic-capabilities-and-obd-compliance/

With the arrival of @Elmue Hud ECU Hacker, exploring the ECU has never been easier.

I started poking around the software and seeing what my Z800 has out of the box.
I was able to make a few changes like RPM limiter and Top Speed limiter.

OLDSKULLTuning.com has a tuned file for a few $$$, did anyone try it out? Looks like we can just load it thru Hud Hacker.
A few other companies also have tunes but you need to send them your ECU, which is not ideal at this time for me.

Anyone got their ZForce tuned? Did you notice improvement, responsiveness?

Thanks

Just wanted to say thank you.

Was able to read all error codes and all parameters on my Canadian 2021 CF Moto Zforce 800.

For those interested, here is my setup:
Acer One S1002 tablet/laptop running Windows 10 Home 32bit (Intel Atom Z3735F with 2GB Ram)
VXDiag VCX Nano GM (J2534 passthru)
HUD ECU Hacker (All credits go to @Elmue)
Connector information provided by @doug80638

Now let see if we can tune these machines and get a bit more power!!!