I have 3/4" BR111 Braz Cherry in boxes in myhouse. It has been in here for almost one month now.

My question is do I need to open the boxes or can they stay closed?

Maybe just open the ends?

Also any recommendations on an accurate moisture meter for someone who isn't going to use it but maybe one time ever?

I can't seem to find one to borrow unfortunately.

Without a moisture meter (an accurite one), you will not KNOW what the moisture content of your subfloor is. No amount of acclimating will help IF there is a moisture issue under your house and you can't tell for sure without a moisture meter. Subfloor MC and flooring MC should be within 2 to 4% of each other. INTERIOR temperature and humidity should be at normal occupation levels (65 to 75 degrees F.) and 45 to 50% relative humidity. These are the ideal levels throughout most of the country with some exceptions in the dry desert areas and the high humidity, gulf and seaboard areas. Shop around for a wood moisture meter. Maybe a lumber yard will let you borrow one.

Are most of them fairly accurate or are there some to avoid?

I have been in my house 3 years. It has a basement below where I am installing the hardwood and I maintain consistant temp and humidity.

Thanks