This is more of a question about piracy than about emulation itself. Emulators are not illegal, as much as the big N pisses and moans about it. At least, as long as there isn't copywrite protected code being used in said emulators (that IS illegal).
As for the ROMs themselves, that is a whole different can of worms. But, at the end of the day,
piracy will always win. As long as there are digital archivists on the internet, there will always be people preserving history, whether the companies hate it or not. New websites will always pop up, and there are always websites popping up in areas where copyright laws can't reach them (though DDoS attacks are still a thing, and are often what is employed to take these websites down, like what happened to archive.org a while back). I know of one particular website that popped up years back, and though they changed names at least once (that I know of), their current iteration is amazing. They also host the hShop, which has been an absolute boon to 3DS software preservation (I believe they have achieved 100% preservation).
The problem is that you have to stop using google as a search engine because google is literal dogshit trash-tier garbage as a search engine now (and has been for over 8 years now). Stop using google search. Use other search engines (startpage is a good one, and though duckduckgo has turned into trash as well, it's still a million and a half times better than google). You will find ROM content eventually, and it's never going away.
Now, if you want my two cents on emulation in general...
Hardware emulation is the future, at least for the first 6 generations of console gaming. Though, let's be honest here: the first 6 generations of video games are really the only ones worth worrying about (even though I fully support data archiving of everything; I just don't find the gen 7-9 console gaming experience and library to be all that impressive or impactful, but that could also be due to my age
). Hardware emulation breaks wide the dam of accuracy of game consoles that nearly all software emulation can't truly replicate. Imho, accuracy should be the #1 thing emulators get first, and then work on the bells and whistles from there. And yes, I know how hard that is, which is why I don't dog on software emulation whatsoever for not being as accurate as I'd like. Which is why I was so happy that hardware emulation has not only become a thing, it's thriving with the immense success of the MiSTer.
As long as there is demand for these older ROM libraries, there will always be these websites where you can grab them. They just have to hide themselves better now due to the use of weaponized DDoS by these corporations who don't want to compete with their older libraries (because then the lie is exposed that the modern video game industry is healthy; which it
isn't). Private, closed communities have started becoming popular again. More websites and communities are starting to go back to how things were in the 1990s and 2000s with completely closed off communities where quality control is easier to maintain, and even more websites are going the completely sealed off route unless you know someone who is already in the community, a la BakaBT (this is showing my age here because I was there before they completely closed off their website to outsiders), and that one BEMANI HDD dump community that loves to shit all over the poors (and hates when their hdd dumps inevitably get leaked because they are actual assholes and aren't dumping these hdd's for archiving, but for the status of having something they shouldn't and laughing at the people who don't have what they do; yes, they are this petty).
Just keep your ears low to the ground, and if you haven't already built a home NAS to perpetually save all the ROMs you can, then you really need to start investing in one that is both redundant and can handle bit rot. Because with just how much worse the internet has gotten in the past 5 year (after basically losing the old internet back in 2014ish when games journos got exposed for their decades of lies and opened up pandora's box, ruining it for everyone afterwards), there may come a time where you can't even get on the internet without some form of ID. (We really are turning into a cyberpunk nightmare, just without all the actual cool aspects of cyberpunk...)