The same driver in a sealed enclosure will play lower in frequency than will the same driver in a ported one,
Kind of/sort of. Given the same driver in two ideal cabinets, the ported version will have a lower -3 dB, but since the slope is 4th order (24dB/Octave) instead of 2nd order (12 dB / octave) at even lower frequencies the sealed will catch up. I encourage you to grab a box simulator to prove this to yourself, or look up any woofer in the Madisound woofer list and compare the -3dB points of their recommended cabinets for just about any woofer. Here’s a random example:
https://www.madisoundspeakerstore.com/approx-10-woofers/satori-wo24p-8-9.5-egyptian-papyrus-cone-woo...
As you can see here, the highest -3dB point is achieved with the recommended sealed box.
but with lower output above resonance.
Simply not true. Again, with the same driver in 2 ideal cabinets the ported vs. sealed cabinet has exactly the same output above resonance as the cabinet volume and alignment is no longer involved and is purely a function of the driver motor. This is true for all open back drivers, not just woofers. This is something I actually learned in audio engineering class with Dr. Leach ages ago. I encourage you to read any book on speaker design to further your understanding.
Best,
E