Rather, pwsh converts : to ;, which translates to a termination when executed with pwsh, and reads everything following it, instead of the actual filename, then spits out this error:

filename:
foo 1:1.png

Error:
doskey /exename=pwsh.exe e114=Start-Process .\foo 1;1.png
The term '1.png' is not recognized as a name of a cmdlet, function, script file, or executable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.