I've been running a third-party grip on my 90D for a while and honestly its been super solid. You definitely dont need to spend a fortune on the official Canon one just to get through a wedding. I picked up the Neewer NW-90D Vertical Battery Grip for Canon 90D 80D 70D and i'm really satisfied with how it holds up.

• The shutter button is actually quite tactile and doesnt have that mushy feel some cheap ones do.
• Build quality is sturdy enough that it doesnt flex much when im using a heavy flash.
• I havent run into any of those weird battery drain issues lately. It basically doubles your shooting time which is huge for a long day. If you need it fast, its a safe bet that works well and feels decent in the hand. Let me know if you need help with it.

If you want to stay under budget, the Meike MK-80D Pro Battery Grip with Remote for Canon 90D is a solid bet. It's built decently well and the shutter button has a nice, tactile click instead of feeling mushy like some cheap clones. Regarding battery drain, it's mostly an issue if you leave the camera sitting for weeks. For a wedding, you'll be totally fine. Another option is the Mcoplus MK-80D Vertical Battery Grip for Canon 90D. It lacks some of the refined texture of the official one, but it works fine for a fraction of the cost. If you're worried about power, maybe grab a BM Premium LP-E6N Battery 2-Pack with the leftover cash. Its always better to have extra juice on a big day anyway. Honestly, the 90D handles third party grips way better than the older bodies did.

^ This. Also, over the years I've tried many cheap grips and the Vivitar VIV-PG-80D Battery Grip for Canon EOS 90D is actually decent for the price. I grabbed one as a backup last year and it feels surprisingly solid in the hand. Shutter is clicky, not mushy. Ngl, those battery drain rumors are mostly from people using knockoff cells. For under fifty bucks, you'll be fine for that wedding.