I was at the JC Raulston Arboretum in Raleigh, NC. They have a pair of Sabal Brazoriensis palms grown in deciduous shade and planted as 5 and 7 gallon plants in 2009 (https://jcra.ncsu.edu/horticulture/our-plants/results.php?search=brazoriensis). My understanding is that these came from seed collected in habitat.   Here is the larger one but it didn't have any inflorescence this year.   Here is a smaller one with inflorescence. It has some seedlings/smaller plants