honoring the wishes of what is currently my last surviving relative (who I still remain in contact with and love dearly). Not to mention whatever might be a part of any legal stuff pertaining to her will. (which I know hardly anything about and still makes me panicked just typing about)

Regardless of what you ultimately decide about the ethics of it, consider that ultimately it is your life, your decision, and there are other ways to invest money. It’s really unlikely that the will is going to effectively prohibit you from doing something with it other than becoming a landlord, not sure that’s even possible. If you really want to prioritize honoring their wishes you can, but in the end you are the one who is going to have to actually live the life you build for yourself, not them, and no one has a right to make that kind of decision except you. Use your own judgment about what future you want and don’t feel guilty for acting on it.