We don’t have any information to share yet regarding the implementation of purchasable MTX. Our priority is getting Last Epoch ready for an official launch next year - and that means focusing on content such as classes, specialization trees, and endgame. 
I would suggest keeping an eye on this support article where we track the MTX from supporter packs which are currently implemented, and this category if you’re also interested in other supporter pack contents such as the soundtrack. Thanks for supporting us!