There's no website or tool that I'm aware of to do such a pre-upgrade check for IOS to IOS-XE. That said, I've done several without issue. Just about all old commands carry forward.
One thing indirectly command-related is to make sure you have the same license level on the new switch (i.e. lanbase, ipbase or ipservices). If your new switch has a lower license level and you were using features that require the higher license level on the old switch, those commands won't be parsed on the new one because the features aren't available without the necessary license.
To verify, you should connect to the physical console port and log the output to a file while the system loads. Any commands that aren't parsed or have been deprecated will be logged as exceptions during the boot process. You can do this using the old switch configuration file loaded onto the new switch in advance of the actual cutover and resolve any issues ahead of time.
