for android apps, the mobilism forum is great, thoughb only questionably safe, I guess. it's all one click hosters, which sucks, but the apks are usually small enough in filesize to not make it a big deal. Just come armed with a good ad blocker, I guess. You can also try your hand at cracking/patching apps yourself, right on your phone with stuff like lucky patcher
for switch, I'm not sure, they'll usually be among other gaming torrents on all sorts of trackers in my experience
If you have an unlocked bootloader phone with a working xposed module, see if you can use an app such as Xprivacy to block all the permissions of every pirated app just for good measure. This method bypasses the Google permission system and apps aren't able to detect blocked permissions this way.