If the ally is dead you would need a revivify scroll. I don't think we should imbue healing potions with the ability to raise the dead even on a natural 20.
Honestly a dead ally is easier to deal with than a downed one since you can revive them somewhere safe. Which technically isn't a 5e thing either. They should revive in place and it should only be usable in that combat they died in and not later.
I mean its so odd that people are up in arms about potion tossing but Revivify = True Resurrection - "Oh yeah, that's fine"
So, I am aware that the spell revivify allowing you to move the ally is not raw, but I am fine with this change because its a videogame and because of potential issues. Say one of our characters gets pushed off and dies on a ravine, if they get revived down there they are stuck. In TT you could climb down there, revive them, and then climb up. But in this game, that can be an issue with some of the set up areas. Letting us choose where are character is revived fixes that issue, ensuring we don't have a situation where a character is genuinely stuck nor have a situation where a character is stuck in a death loop because of some weird glitch or situation that normally would be RPed in TT but can't be handled in a videogame easily.
That said, I feel like the use of that scroll should be limited to characters who would have the spell on their class list, so clerics and paladins I think, if it is meant to be revivify. Otherwise, make it into a scroll you get from the skeleton instead of anywhere else and rename it to something completely different so Revivify can work as RAW and so the scroll can do its own homebrew thing (ideally with its supply being lower cause in my playthroughs I end up with like 20).
And yeah, unless the potion is explicitly about reviving the dead, no potion should do that, regardless of roll.
