Yehudayona- the chofetz Chaim lists all mitzva that we can do while in galus without a Bais hamikdosh. Yes , you can do yibum without a Bais hamikdosh, but you can’t bring bikkurim. Now it’s true that the minhag is that we choose Chalitza instead if yibum today and honestly I’m not sure how long that goes back however the point is thats it’s doable in galus.
Careful how you speak about a gadol hador!