What are the pros and cons of modifying a Nintendo Switch?

I know I'm really late to this thread, lol:

As someone with a hacked V1 Switch: There's no cons as long as you follow the guides. If you do the initial hardware part of the hack wrong, you can cause a brick, so be careful if you use a paperclip (it's unlikely as long as you follow the guides, but if you poke the wrong pins then you'll have issues). To be safe (you absolutely don't have to, though), I'd recommend buying a premade jig (one of the hacking subs used to have a guy that sold them for about $4 with shipping included).

As others have said, you can run the emunand and keep it offline to prevent a ban. If you are banned by Nintendo, you simply won't be able to access their online services.

I highly suggest hacking it, it's been one of the best hacked consoles I've had (3DS with the custom themes was funner though, but I've also got a Wii U and PS4 that are hacked). The best part of a hacked Switch is mods, though. Modded Breath of the Wild, Tears of the Kingdom, Super Mario Odyssey, Smash Ultimate, Mario Kart 8, Skyrim, Fire Emblem Three Houses, Fire Emblem Engage, etc.

The piracy community tends to recommend Tinfoil (for installing games), but unless things have changed (closed source, dev isn't the greatest guy), I'd avoid it and use Awoo instead (Goldleaf is fine, but doesn't check files). You don't need Shops at the moment to find games (access by using Tinfoil), but if you don't use them, you do need a good adblocker and adsbypasser (like Fast Forward). I'm not a fan of shops personally, but I believe there are some that have saves, so you may eventually want to look into that. Unfortunately, a lot of Switch Piracy is locked to discord (which I won't use), so I can't provide you with much more information on shops.