I have the beachball when searching for anything with my iMac on Monterey

If the same problems occur in "Safe Mode" there is a strong likelihood of hardware failure, despite what any testing utility may conclude.

I ran Drivex with no errors shown.

I am not familiar with that product but it has been my experience that using them is a waste of time. I have example hard disk drives that are operating in a conclusively failed state — barely working — yet Disk Utility and third party utilities like DriveDx conclude there is absolutely nothing wrong with them.

On the other hand if it reports a definitive failure it can be considered a conclusive result. Same goes for using Apple Diagnostics, although you are welcome to try it: Use Apple Diagnostics to test your Mac - Apple Support

Conclusively determining a hard disk drive is operating in a state of failure is frustratingly difficult, and is best accomplished anecdotally. Unfortunately it's not easy to do that with an internal storage device, but what you can do is install macOS on an external drive (preferably a fast one) and observe how well the Mac functions when using it as a startup drive. Booting from it will take considerably longer but once everything is running and cache files are built it should not be objectionably slow and you should not encounter the "wait cursor" as frequently as you describe. I have done this with USB3 hard disk drives with your model iMac with good results. An SSD would be even better.

(I understand the inability to load App Store content will frustrate your ability to download and install macOS on the external drive.)

If the Mac operates acceptably well running from the external drive, that's all you really need to know to condemn the internal Fusion Drive. They can be replaced, preferably with an aftermarket SSD from a vendor known to support Macs. Apple won't do that but an Apple Authorized Service Provider might be able to.

The yellow icon with the red check mark appears in the task bar, bounces for a few minutes and then disappears.

If launching EtreCheck causes its Dock icon to bounce for minutes (!!!) before finally disappearing, that only lends additional support to a diagnosis of startup disk failure.

In what probably amounts to desperate measures try resetting that Mac's SMC: Reset the SMC of your Mac - Apple Support.

Then, start looking for a place to get that Mac fixed. You can start with Apple Support of course: Official Apple Support, but if they conclude the Fusion Drive is at fault then ask where you can take it to have it upgraded to an SSD.

Please determine if the same problems occur in "Safe Mode": Use safe mode on your Mac - Apple Support.

What's preventing you from running EtreCheck? If you already downloaded it, simply launch it again. If you need to download a new copy the link is here: https://etrecheck.com/

BTW Drivex was another utility reccommeneded by other threads in this community.

Not from me. Not because they are worthless, using them is a waste of time. Why? They will either confirm something wrong that only Apple can fix, or they will report "no trouble found" when trouble obviously exists such as the HDD I used as an illustration. Either one results in the same conclusion: the Mac is broken. So using them just wastes your time.

The only utility I recommend because it is useful and can result in something you can act upon is the one that we can't get to work... which served to confirm what you already know. In fact it was useful, in that sense.

I see three choices at this point.

I suggest (1) (3) and (2) in that order. (1) because whatever you buy can be used for a number of other purposes now and in the future, (3) because that iMac is "old" (according to Apple) followed by (2) if and when you replace it with a useful brand new Mac which will hopefully serve you for a similar period of time, and when you have the cash and motivation to keep the older one in service — if for no other reason to spite Apple's insistence that it's old and worthless.