I hadn’t considered unlocking difficulties as metaprogression, but yea in that case I think it’s a fair mechanic (to be clear, I tend to drop these games when I get to the inevitable difficulty spike at the final area/boss, so I haven’t really experienced it, as the only one I can clear is Rabbit and Steel which has a traditional easy/normal/hard/harder selection).
Unlocking content to ease players in I think is weird and counter productive, as often even failing gets you further in the process and you might not have learned what the game was trying to teach you by delaying something. You might then be in a slightly harder game without having progressed as a player.
What I really don’t like are the permanent leveling/modifiers you find in games like Hades. I feel like they go against the basic idea of a rougelike/lite, since you can/need (depending on the game) to grind.
Excel does it for its formulas. It ends up being just a pain in the ass when you are looking online for info (which means it ends up increasing the barrier of entry, as most stuff online is in English).