The way I read the 1st linked suggestion, it’s about an option to get cross-library collections. Not primarily to have cross-library collections for movies only (although collections are limited to the same media type at the moment in addition to media of the same library… except you consider the handling of same-name collections).
As you pointed out, the common approach towards what you describe is having a playlist (see Watch crossover episodes of several series in-order). Just trying to wrap my head around your suggestion… would you actually want to add all individual episodes of various Marvel shows in between the movies or should this also allow mixing of seasons or entire shows? I’m still having a hard time to see the actual value add (beyond having a sequential playlist) – which shouldn’t diminish your suggestion… it’s just not really clear to me.
