I feel your pain re sample management. I dream of the day there’s an iOS version of the Transfer app. I also know what you mean about creating your own sounds - I started with the m:s and quickly found I wanted to get into more sound generation than the m:s could offer.
So I got the digitone (and the digitakt… and re-bought an m:s in the end, but that’s by-the-by) - you get the elektron sequencer you’re already familiar with, and a vaaaast synthesis engine, 8 voice poly, multitimbral. Means you can run drums on one track and still have 3 tracks to play around with.
I dunno your budget but it’ll probably end up cheaper than eurorack
And might as well keep your m:s too - resale isn’t that high and with a bit of time using other synths you might see the value of its immediacy.