Yes, it is possible to be a “landlord” in this fashion and keep your ethics intact. Just don’t be an asshole about it.

Charge a reasonable rent for the other apartment, don’t harass them if they are a fewdays lats with rent, keep the place updated and well maintained. And certainly don’t let an AI tell you what to charge. The best possible situation is to rent to a young person just starting out or a young family, who can use the time renting from you in a non-predatory fashion to build up savings to buy a place of their own, then rinse and repeat. Wouldn’t that be fulfilling?

On the other hand, though, look into the basic tenant law in your ares so you know what you’re getting into. Some locales are notoriously tenant friendly. You might rent out your space to someone who signs all the paperwork saying that they will pay rent, and then when the time comes they never pay. This might persist even after their lease is up, and not move out when required to. But as a landlord, it will be totally your choice to decide what to do in that situation. While the law may allow you to evict that person, you don’t have to escalate that far on day 1. The choices would be up to you. You can choose grace and patience if you want. It may not always be enougn.

Your relative is doing this to give you a sustainable path to a better, more stable life. While this path is not for everyone, it doesn’t automatically make you exploitative.