Good one tomooh! Sounds like you have got it nailed. Yes. The best learning waves are the ones that break with whitewash sliding down the face of the wave & into deep water where the whitewash slowly subsides, leaving you riding just the swell. This is where the learning of turning & pumping comes in.
Big waves at head high are very difficult unless you catch them after they have broken when the whitewash subsides. Usually at the shoulder.
Small & weak waves are frustrating & difficult with small & medium foils too unless you get the foil up & running early as the waves break as well as pointing along the wave face. Otherwise you will just stall or sink.
I spoke to a surfer I know who is good at SUP & prone & has had about 8 to 9 months of foiling said that the hard part of prone foiling in the beginning was obviously the pop up where he found it difficult to keep the nose down when getting up. So maybe hands more forward when getting up.
And with all foiling. Feet positioning is the most critical as you probably know. I am so glad I forced myself to paddle & ride my sup in the surf stance when I started foiling. So comfortable now. My front foot is always positioned over the centre line. The back foot only has to slip back to the tail pad or pad block so my foot is over the mast when catching a wave. Less to think about.