Are international folk able to join in the consumtion of the goodies at least? I was really looking forward to going, getting a piece of merch will fool my brain into thinking I was there :D
for attending the event and the concert, there isn't a limit in terms of nationality, the only "limit" is that you must have been in Japan for at least 14 days before the event. the main problem for many overseas fans is that Japan still has its borders closed, and probably will reopen them only at the end of the year or by next spring (nobody really knows..).
for the goods, you can buy them from the official goods online store
初音ミクオフィシャルグッズストア、初音ミクのイベント関連グッズを販売しています。マジカルミライ/SNOW MIKU/鼓童×MIKU/京まふ
miku-store.com
also, compared to previous years, the exhibition tickets are very limited in numbers (because there is a limit of maximum people inside the exhibition venue), and you have the guaranteed exhibition ticket only in case you have a special benefit concert ticket (from accomodation plan or travel agency), but the difference from previous years is that the exhibition ticket can be used only on the same day of the concert ticket (´・ω・)