The way I read the documentation, the only way to on-board a new user-role with a read-only account is to create that role and then manually mark each field as read-only, one-by-one. This seems ridiculously tedious, so I'm hoping someone can tell me an easier way that I've missed.
We're in Sugar 9 now, if that matters, but planning an upgrade to 11 as soon as it launches.