6804 and 6805 are standard industrial sealed cartidge bearings. A bearing is a bearing, unless they are ceramic or something else really special. Blue seals (like your link) are nothing special. Green seal is a bit better grade of bearing. In those thin-section bearings, number/size of balls are probably going to be the same no matter the grade. If you live in/near a town of any size there is probably an industrial bearing supply (or two) that can match those numbers for you.

Now, the difference between 6804 and 6805: 6804 is a 20x32x7, meaning your axle will fill the ID. 6805 is a 'nuther animal: it is 25x37x7. there must be a bushing sleeve that slips through the inner race that the axle then slips inside of. Do I understand that you are converting a QR front hub to 20mm thru-axle? You will need a bearing with the sme OD as what's in it and (easiest way) 20mm inner race ID. Your hub will be either a 2-bearing hub (likely) or a 4-bearing. That is all you will need for quantity.