We built our hosting around exactly these requirements.
NVMe SSD storage and a CDN keep listing galleries loading quickly, even on a phone at a show house.
Buyers submit names, numbers and financial context through enquiry forms — SSL encrypts all of it.
Individual agent addresses on your agency domain, which is what sellers expect when signing a mandate.
Listings and enquiry history are backed up every day, so a bad update never costs you a portfolio.