I ordered 5 of the HT SOLAR 375W 72 CELL MONO PVs, and they were packaged very well and shipped promptly. The only downside was they showed up before I got a notification, and I was not expecting them when the shipper showed. No big deal, they are good to go.
Figure out max input Volts DC from your panels that the Ecoflow Delta will take. It’s in the book.
For example, the delta pro is rated to 150 VDC, but you must take into account the added solar efficiency from extreme cold weather. So err on the lower side if in colder climes, eg 48 volt PV x2...
I’m in a similar situation.
Each EDP will take 1600 watts, so you could go with 4x400 as long as you don’t wire it with more than 150 VDC, per Ecoflow.
So if you had two EDP units, you would want 1600 W to each unit, totaling 3200 W.