www.pcworld.com/windows 11 unsupported pc disables updates Microsoft will continue to support at least one Windows 10 Semi-Annual Channel until October 14, 2025. If you do not own any permanent recovery media and need a key I suggest you buy PRO windows and keep it because you wont be able to get this after 2025. The disk can be used to repair or recover any dell model that works with windows 10 up to and including models from 2006 and newer like the Optiplex GX620 745 755 760 780 790 320 360 380 390 960 980 990 3010 7010 9010 3020 7020 9020 etc. [URL]    
Microsoft is announced  that it won’t block people from installing Windows 11 on older PCs. Microsoft has recommended hardware requirements for Windows 11.  Restriction to install the OS will only be enforced when you try to upgrade from Windows 10 to Windows 11 through Windows Update. This means anyone with a PC with an older CPU that doesn’t officially pass the upgrade test can still go ahead and download an ISO file of Windows 11 and install the OS manually. Neither Dell nor Microsoft support older hardware that may have issues such as spectre and meltdown issues as well as being very slow.
Windows 11 will work on older models but it will not be a FREE upgrade.