How do I check my sp_Blitz/sp_WhoIsActive versions across multiple servers/databases? I have a bunch of SQL Servers registered within my SSMS, lots of different SQL versions, editions and DB compatibilities.

I want to check out if any of those servers have any of the sp_Blitz or sp_WhoIsActive stored procedures installed, and which versions they are.

I know I can right-click on my Registered Servers group and open one query window that connects to all the servers in the group, but is there a reliable way to check which SProcs and versions I have?
For sp_Blitz, there's an enhancement request filed at Github to add outputs for version, and if you'd like to influence how the work is done (or contribute code), you're welcome to leave comments over there.

For sp_WhoIsActive, the author Adam Machanic is considering adding an output to the Messages tab each time it runs.

Until then, Oreo's suggestion above of checking the code is the best one. We won't break that intentionally - we haven't changed those strings in years, and don't intend to start, heh.