I’m not sure I know what you mean by diagnosing, but it’s usually a good idea to use the same distro you’re having trouble with.
Adding on to other suggestions, if you’re not aware of Ventoy it’s a very handy tool. Using it you can have a USB drive with several live images on it which you can choose at boot time. Great for quick testing, just drop an ISO in a folder!
What makes you think that? Their website has instructions for installation via a Linux box. https://www.ventoy.net/en/doc_start.html
I’d go with a live image of whatever distro you’re most familiar with. I usually go with the arch iso or endeavor os if I need a GUI.
I’ve been using Knoppix for this purpose for like the last 2 decades.