I would totally agree with your thoughts, either 304 or (better still) 316 Stainless are excellent in terms of reducing cross contamination to acceptable limits with bio application resins.
Our personal preference in terms of risk reduction being 316 stainless due to its much better resistance to acids.
Recently on one of our printer designs we have been using a two part build plate with the base structure in 316 stainless and a print build surface consisting of sheet 420 grade stainless (0.8mm thick) held to the 316 base structure with N42 magnets on a 50mm centres matrix (10mm dia x 10 deep magnets) The end result is a very stable build plate that can be removed after the print and flexed to separate the print.
Even prints that you would expect to be very fragile remove easily using this method from the build plate and prints that have a large surface area in contact with the build plate are now a joy to remove (irrespective of how well the resin grips the build plate… No scrappers, no force and no damage during part removal
Surface finish of the 420 stainless build plate is vapor blast to 3um.