Hello @04032588 - Thanks for reaching out & posting on the MS Q&A channel.
You're right about there being scarce guidance on migrating from one ISE to another; and given the impending retirement status for ISE offering, I doubt that there is going to be such documentation -- although we do have dedicated guidance on migrating from ISE to Logic Apps Standard. As such, this will likely require support from our internal SMEs. Do you have an active support plan?