This is so easy you’re gonna spit…

#Merely Set the ISE alias in your $Profile in PS7
#NOTE:Remember to save your PS5.1 $profile to the $Profile path for PS7. They are not the same, in other words

CommandType     Name                                               
Alias           ISE -> powershell_ise.exe

Like this:

set-alias ise -Value powershell_ise.exe -Description ISE -Option Constant -Scope Global -Force -verb

#-OR-
#Just type ‘powershell_ise’ at the PWSH.exe prompt with the path\script name to edit in ISE