Your fenders can help define the problem. From the outset, I noticed a lateral wobble of the tread of my front Schwalbe Pickup as I rode, viewing it past the end of the fender. With the bike on the center stand, I found no such runout on the back tire.
For a rough measurement, I held a felt tip marker against the front fender to leave a line along the center of the tread. It was about 3 mm. It surprised me that I didn't feel it when I rode. The beads looked even all the way around, but some e-bike beads can appear to be seated but not be quite right, so I like to inflate to maybe 5 psi and ride a few yards to squish everything into place before inflating fully. I must have skipped this step when I installed that tire. I drew off pressure, rode a few yards, and reinflated. The runout was gone.
If your tread is eccentric, I guess you could detect it by bracing your finger against the edge of the fender and letting it drag the center of the tread.
If the leak wasn't too big, a rechargeable pump could have gotten you home.