Yes, a wildcard certificate from Let’s Encrypt (or even any other CA) would be apt for the kind of use you wish to put it to.
I don’t think you should let your past experiences influence your future decisions, else a stumble you had as a toddler would inhibit locomotion.
I use a SaaS hosted on a Virtualmin server at crm.indiax.com and a wildcard SSL is working perfectly on it. If you have newbie questions, see