Make sure that whatever artist you decide on does it at a VERY high resolution and sends the file as a PNG (trust me, you don't want to be seeing jpg artifacts on your pillow).

Dakimakura pillows are about 21" by 60", at 300 dpi (standard printing resolution) that's 6300 x 18000. You could do 150 dpi, which would reduce the size to 3150 x 9000, but it won't look as clean or sharp.

The minimum you could probably do without it looking like crap might be 100 dpi, which is 2100 x 6000, but that won't be very detailed, clean, or sharp looking.

wow, that is some really good advice, i know what i'll look out for next time when i want to commission dakimakura pictures so thanks <3

I know that, I've been looking at sites that do them. Sites in question ( Like https://www.furrydakimakura.com/ ) want 150 DPI instead of 300; but that's still really high-quality. If it wasn't needed, I'd have probably have just gone for one of the artists I regularly commission