Working on it and now the A/C stopped working?

Well, I finally found some service info on engine temps and the warning messages, according to this you were receiving the Engine High Temp message because the coolant temperature was getting above 260f, and being below 255f is apparently within normal operating temperatures, which is why the message turned off, seems very high to me,
And 269f is where you will get a critical high temperature message.
The gauge on the Cluster reads 100-260f, that's its range, still you shouldn't see the ECT glitching out, But I guess 220 is within spec, that explains why you aren't seeing the fan on High at that temperature.
Are you still seeing the coolant boiling in the reservoir?

Okay, well, if you do decide to change out the ECT sensor, just make sure you get an OEM one from the dealership, or rockauto carries OEM parts a lot of the time. You can flush the radiator too, coolant systems build up an acidy type of sludge over time which is what causes most heater cores to eventually leak, so it's good to flush them out with just plain water once a year, I know it's cold where you are now, so that will have to wait, but just things to keep in mind. Hopefully things will be ok over the winter for you, we haven't really gotten into the cold days yet down here. So I'm still working outside on mobile calls.

Well, it really depends on how much you would want to spend, and with aftermarket scan tools like Autel, Topdon, Launch X431 etc., they each will be limited with bidirectional controls and special functions depending on the manufacturer. Some have more control, some have less. I do not own any Launch scan tools, I hear they have some good functions, but I think it costs more. Autel is probably the best besides an actual OEM manufacture scan tool for one make of vehicle. You want one that states it can do full system scans, so every module in the vehicle, that way you can read codes and live data from every module as well.
The cheapest Autel that has some bidirectional controls is either the MK808 or MX808, I think the MK is an upgraded MX. Its about $500. And you won't really get anything with bi directional controls for under that price. Launch has some listed in the $350 range but with scan tools you really do get what you pay for. Don't buy any from AutoZone and such, their scan tools look good, but I've been hearing them fail prematurely after not even a year.
With Autel you will also have a yearly subscription for updates, it's about $120 roughly, I don't remember exactly how much, I have a Topdon as well, but their good scan tools will run you at least a thousand.

Here's an Autel on amazon just for example:.
https://www.amazon.com/dp/B0744B55QV?tag=bgus-361562-20

And Autels home page. Also check aeswave,com
https://www.autelonline.com/

The special functions page is for when replacing batteries, injector coding, some calibrations stuff. I definitely use my Autel the most since I work on pretty much any vehicle make that I need to. Something else to keep in mind is with many of the newer vehicles, somewhere around 2018 and up (again depending on manufacturer) scan tools are requiring registration with AutoAuth to access the vehicles network through its gateway module. This is due to newer vehicles having Wi-Fi and wireless updates and is a security measure. If you don't plan on working on newer vehicles you don't have to worry about that so much. I recently worked on a 2017 Ford F350 DSL and didn't have any issue with using a scan tool. And a 2019 Honda CRV and didn't have any issues with that, but things change in this industry every day. Sorry for the long post.

I've never used Xtool before, they are a newer company, I would go with an Autel MK808 if you're going to spend a few hundred anyway, it's a much better tool, I'm not sure who makes Xtool either. I just know how good Autel is.

Its really up to you, there's no way to actually know the tools performance and how well it will hold up until you have it and try it for a year, I've had all my scan tools for many years, one I've had for over 20 years, It depends on how much you'll plan on using it to I guess, if it's only going to be once and awhile on one vehicle, then paying for a higher end tool might not be for you. But we all take a risk with the gear we buy honestly.