So one thing I'll put forward here on Larian's side (sort of):
In their game currently, where time itself has no meaning, they have the opportunity to simply treat ritual spells like they treat long casting time spells - such as prayer of healing. In BG3 currently, Prayer of healing doesn't take a long time to cast; just an action like most other spells - instead, they constrained it so that it can only be cast out of combat.
They could easily implement this for ritual spells, but would need to make a choice as to whether they want ritual spells to be ritual *only*, or whether they want to add play choice on whether to ritual cast or not. The 'ritual' version would be out of combat only, like PoH, and would not take a spell slot; it would be available to wizards as long as they know it, but only available to non spell-book classes if prepared, etc.
doing it this way would be the easiest, simplest, path-of-least-work method of putting ritual spells in the game, so you can bet with fair certainty that if we ever do see them, that this will be how it is managed.
Personally, "Doesn't take any time, but only out of combat" is a "Change-For-Video-Games" tweak that I actually support and accept as a good compromise.
