We have certainly thought about this. Micro transactions are tricky business there are so many cuts taken along the way. One refund on a 2 dollar donation can end up costing you 1 hour in time, totally erasing the value of 20 other donations that follow.
My feeling here is that the only way to offer a service like this to our customers would be by introducing a virtual currency of sorts (eg: roblox or discord boosts) then you would spend that virtual currency to donate. This allows for larger blocks to be purchased and heavily simplifies refund situations (where it would not costs us actual money, only time to refund a mistaken donation)
That said, nothing like this is on the roadmap yet, it would be a gigantic project.