Last week I did a copy of a one page document (advertising) in Indesign and pasted to Affinity Publisher – and it was a pretty much a perfect match – with editable text. I just wanted to see if it was possible before recommending it to a client. It was. This of course requires you to be have both Adobe Indesign and Affinity Publisher installed on your Mac. Would be nice though being able to open IDML-files, but there's probably a lot of restrictions from Adobe – hefty price tag – to do so.
Adobe did the same when 'running over' Quark in the early days – when Quark didn't missed (wasn't ready to deal with) a Mac OS-upgrade) – allowing switchers to open Quark documents in Adobe Indesign.