Third-party kernel extension preventing Mac from successfully booting

+1 on EtreCheck. It safely allows a data-driven evaluation in this setting where we can neither see nor touch your computer. We can quickly and within the limitations of these forums help you determine what issues are at play without our playing a protracted game of "20 Questions" with you that could go on for days. 

EtreCheck Pro is available here:

https://etrecheck.com/index

The free version will do nicely for this purpose, although the app is worthy of our financial support. It will not reveal any personal or secure information.

You cannot do a traditional copy/paste the report without it becoming garbled. You do not need to highlight the report before using Etrecheck's embedded COPY command as shown in this excellent user tip on how to post long text reports like EtreCheck's into a forum response:

How to use the Add Text Feature When Post… - Apple Community

Please post the entire report. What seems insignificant to a new Etrecheck user can hold answers for those of us who have reviewed thousands of those reports. 

Some background: If you get an alert about a system extension on Mac - Apple Support

The Etrecheck data can help identify the app and the kext at issue, and somebody can provide the command needed, if the app itself doesn’t remove the kext. Please post that.

Entirely for future reference — at for now — and posted here solely so that I don’t have to go look for this text again…

Per Apple: Unloading a kext on macOS 11 and later requires a call to kmutil or kextunload, followed by a system reboot. The kmutil tool builds a new kext collection without the specified kext, but it doesn’t install that collection immediately. The system installs the new kext collection only after the computer reboots. As a result, the unloaded kext actually remains active and running until the user reboots the system.

For more details, see the kmutil(8) man page.

It may be worth running a free version of EtrecheckPro, available from etrecheck.com, to see what caused the problem. Instructions are given as to how to run a check. When you have the report, under "Minor issues", click on the Review button next to Kernel extensions present. 3rd party kernel extensions are under System extensions. The advice given is as follows:

If it is not immediately obvious which ones are causing the problems, whether to remove them and how to do it, people here may be able to advise.