[Google Pixel 7] simplepinoi177:
In my experience, usually when it states "best drivers already installed" happens when you simply "search automatically for drivers" or DO NOT select the "Let me pick from a list of available...". If you do the "deeper method", it would not state "already...best drivers installed" but would (almost forcefully) install the driver over the existing one as you are insisting on applying a driver over Window's supposed "best driver".

But seeing that it shows up as "Unknown USB Device" with a yellow triangle does show that is most likely the reason why your computer is not recognizing your device as an ADB device and that you cannot run adb commands. I'm unsure how/why it isn't recognizing it (but it does fastboot, which is the most confusing part), but maybe it is a hardware or device issue....

I'm afraid by removing/replacing .dll files, something may have inadvertently gone wrong and that's why it's saying the files you have are not "compatible with 64 bit systems". The easiest way to correct this is to do a Windows System Restore from a restore point before you started messing with .dll's, if you are willing to do that. I personally have never had to do what worked for @GodieDan and his method -- so I can't speak too much on it. I believe merely pointing to the .inf file should do the trick and messing with .dll's does more harm than good....but at least he does promote caution and to backup/copy what .dll's are deleted/removed just in case. If you have followed this warning/caution, I would copy the .dll's back and try again -- but making sure you follow the "deeper method"

to the point of clicking "Have disk" and double-clicking the specific .inf file, pressing OK

. If you need even further verification/steps, after clicking "Next" from (supposedly) selecting "Android Recovery ADB Interface", Windows will even warn you on a "Update driver warning" (this is how I know you may not have done this as this would conflict with the "best driver already installed" and Windows wouldn't even bother making this statement)

Unfortunately, with your bootloader locked and "OEM unlock" unticked, there is not much you can do in bootloader/fastboot mode and, more specifically, able to reset/re-install/re-flash the system using the Full Factory (or even OTA) image. As close as it feels that fastboot is detected and some (identifying) commands may work in fastboot mode with fastboot commands, you shouldn't be able to recover anything past that.

You're best bet has always been to go about it how Google essentially goes about it and what they allow on a locked bootloader -- either the stock ROM System Update or flashing the update; both ways using an OTA image (which, as I understand it, cannot be done in bootloader/fastboot mode).

It just occurred to me, but if you have access to a USB-C flash drive (or can somehow transfer files to your device), there is also an option to "Apply update files from SD". I've never done it personally, so I'm unsure if you can simply point it at the .zip file or an extracted file/folder, but if you can update it through that, then you don't need to worry about all this ADB interface connection stuff....

Again, please keep in mind that if you are successful, applying OTA's usually do not wipe the device and start from scratch, so it would be best to then factory reset one more time after successfully applying the OTA update...

I know I direct you to do a lot, so I appreciate you attempting to go along with all of it and I sympathize with any frustration & trouble you feel from the situation and what the directions cause. I hope one of my/anyone-from-the-thread solutions will work out for you!