Don’t make my mistake and read ahead. 6mm may be too close for comfort! 8mm is definitely too far and caused me to damage. Also be sure to read the right manual! I have an XL and it notes 5mm.
Just to report back on this guide, my Pixel 3a XL actually has the gold contacts for the earphone on the opposite side than shown here. Looks to be the reason for it to not work in the first place. Unfortunately I damaged my screen during the repair by pressing too far into the bottom ribbon connector, splitting it, or damaging it in some way it will not function anymore. Just flickers.