Buy vis

You don't farm shards for limiteds, you only buy them for a limited time, sometimes there's a bonus from chocobo with limited areas or corresponding element, but usually no more than 20 even with speed tickets, its absent here because of the 9step and bingo reward

If you wait for anniversary you can get 2 shards per day from barracks

FALSE, the limited shards are NOT absent from chocobo runs. Just have to run the corresponding element. I've gotten 6-7 Winter Vinera shards just today from chocobo runs

But can you get Dorando’s?

I probably get one vik shard per day from chocobo, still doesn't count much toward the 600 goal for 99 and it ends soon