I've been trying to get some steps together to see how to take my app to MacOS but so far it hasn't been working out. If anyone has succeeded in this and could contribute anything to the thread it would be a huge help.

https://github.com/airsdk/Adobe-Runtime-Support/discussions/2088

Current steps tried:

Step 1:
My app was building fine for iOS so I edited adt.log to find the command IntelliJ was using to build and package it, and edited it to have the target bundle instead.

adt -package -storetype PKCS12 -keystore /path/to/my.p12 -storepass xxxx -target bundle /path/to/bundle /path/to/application.xml -extdir /path/to/anes -C /path/to/ MySwf.swf -C /path/to/assets . -C /path/to/icons

Step 2:
Login to your developer.apple.com and create a new 'Developer ID Application' certificate. Choose the G2 Sub-CA (Xcode 11.4.1 or later) option. Save this to your machine and double-click it to install it. It will be added to Keychain

Step 3:
Use this newly added certificate to create a new .p12 file. Inside of Keychain expand it and highlight both it and the private key under it, right click and export to .p12 file, adding a password when prompted. Ensure you update your adt command to use this new p12 file.

adt -package -storetype PKCS12 -keystore /path/to/developer_id.p12 -storepass xxxx -target bundle /path/to/bundle /path/to/application.xml -extdir /path/to/anes -C /path/to/ MySwf.swf -C /path/to/assets . -C /path/to/icons

Step 4:
Go to https://www.apple.com/certificateauthority/ Here you will need to download the intermediary and root certificates needed to sign the build.
First under Apple Intermediate Certificates download "[Developer ID - G2 (Expiring 09/17/2031 00:00:00 UTC)]"
Then under Apple Root Certificates download Apple Root CA - G2 Root
Then also under Apple Root Certificates download Apple Inc. Root ??

Step 5
Install the downloaded certificates into the System section of Keychain.

Step 6
Finally verify your whole chain is valid. Start by Clicking your new 'Developer ID Application' certificate and ensure it says "This certificate is valid" Right-click it and press 'Get info' and look at the 'Issuer Name'
Find the certificate that matches the issuer name and repeat the validation process and look at that certificate's issuer name.
Continue repeating the process until you arrive at the Apple root certificate.

Step 7
Use Java 11 because Harman says that works best

Step 8
Verify your mac can sign stuff by trying the following:

Go to a folder and run:
cp /path/to/AIR/SDK/bin/adl .
codesign -f -s "Developer ID Application" adl
codesign -dvvv adl

Unfortunately even with all of the above and verifying that I can sign stuff I still get the error:
"Unable to build a valid certificate chain for the signer"