https://store.line.me/SC/CreatorsCollaborationSo
now it's finally starting. Submission of stamps for approval has begun already. The sales period, for the time being at least, will start on June 1 and end one year later. After this, if they don't extend the period, you won't be able to buy the stamps anymore but you can still use them, of course.
Division of sales is basically 30% LINE, 35% App market, 25% Creator, 10% ZUN.
Stamps are allowed to be registered in Japanese or English, but unfortunately, it looks like the sales are going to be restricted to Japan only.