The admins of Lemmy.ml are staunchly against any pornographic material being federated to their instance. This stance is unlikely to ever change and you should not expect it to.
Personally I would just recommend keeping two accounts if this is your problem - one general purpose and another for being able to view NSFW.
For what it’s worth, I saw your posts on Yiffit when you found all this out after the fact. It’s a little inconvenient on desktop, but on mobile it’s actually very intuitive to have separate accounts to specifically browse an instance by local. You can usually even have the same display name if that’s important to you as well.
In the future though you always do need to keep instance politics, culture, and rules in mind when choosing a daily driver account because it is important.