As of Catalina 10.15.4, the scripts no longer work.
iTunes can be installed with Retroactive https://github.com/cormiertyshawn895/Retroactive/releases
Retroactive thread on MacRumors https://forums.macrumors.com/threads/retroactive-mac-app-that-lets-you-run-aperture-iphoto-or-itunes-on-macos-catalina.2207898/
Yes, iTunes 12.6.5.3 is working on MacOS Catalina 10.15 Beta 19A471t
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More details soon.
UPDATE:
iTunes 12.6.5.3 & 12.8.2 https://forums.macrumors.com/threads/itunes-12-6-5-3-on-macos-catalina-10-15.2184518/post-27807492
iTunes 12.9.5.5 https://forums.macrumors.com/threads/itunes-12-6-5-3-on-macos-catalina-10-15.2184518/post-27843550
iTunes can be installed with Retroactive https://github.com/cormiertyshawn895/Retroactive/releases
Retroactive thread on MacRumors https://forums.macrumors.com/threads/retroactive-mac-app-that-lets-you-run-aperture-iphoto-or-itunes-on-macos-catalina.2207898/
Yes, iTunes 12.6.5.3 is working on MacOS Catalina 10.15 Beta 19A471t

More details soon.
UPDATE:
iTunes 12.6.5.3 & 12.8.2 https://forums.macrumors.com/threads/itunes-12-6-5-3-on-macos-catalina-10-15.2184518/post-27807492
iTunes 12.9.5.5 https://forums.macrumors.com/threads/itunes-12-6-5-3-on-macos-catalina-10-15.2184518/post-27843550
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