Honestly, dont risk a third-party grip on a brand new body like the R5II. The power draw for that stacked sensor and the Canon LP-E6P Rechargeable Li-Ion Battery is pretty intense. Cheap grips often have slight voltage fluctuations that can cause weird AF glitches or the camera just freezing up mid-burst. Since you're shooting a wedding, you really dont want to be pulling batteries to reset the thing during the vows... I would suggest being very careful here. Stick with the Canon BG-R20 Battery Grip because:

• The build quality actually matches the magnesium alloy body.
• It handles the high-speed communication pins properly.
• You wont get those annoying 'unauthorized battery' popups. The Canon CF-R20EP Cooling Fan Grip is probably overkill for weddings tho. Unless you're shooting 8K 60p non-stop in the sun, the standard grip is totally fine. Bite the bullet on the official one for peace of mind.

Re: "Honestly, dont risk a third-party grip on a..."

• I have to agree 100% with that! When I first started out, I tried to save a few bucks with a cheap knock-off grip on my old DSLR and it literally started smelling like burnt plastic during a family shoot... it was so scary!! I almost cried because I thought I had fried my whole setup. Since you just got the amazing R5II, you definitely want to keep it safe and sound! Honestly, the official gear is worth the peace of mind. If the Canon BG-R20 Battery Grip for EOS R5 Mark II is just way too much for your budget right now, have you thought about skipping the grip for this wedding and getting a high-speed power bank instead? I love using the Anker 737 Power Bank 24000mAh 140W because it supports the Power Delivery standard that the R5 series needs to actually charge while the camera is off or even just to top it up fast during a lunch break. It is a fantastic lifesaver! You could also check for open-box deals at some of the big retailers to save some cash. Every little bit helps when you've already spent so much! Also, dont even worry about that Canon CF-R20EP Cooling Fan Grip for a wedding. Unless you are shooting non-stop 8K video in the hot sun, you wont need the cooling. You are gonna do such an amazing job in San Diego! Just stay safe with the power and itll be great!!

@Reply #2 - good point! Ive seen way too many horror stories of melted pins over the years to risk it on a body that expensive. Honestly, if you're just doing a San Diego wedding, you probably dont need the fan version unless youre shooting 8K raw. I think I heard that the basic official one handles heat fine for standard shooting. Maybe just rent it for the weekend if the budget is super tight?