i wouldn't trust the life span of a used pre hacked switch. They all can be hacked as i understand it so far by either just software or the cheap dongles that come with the usb part and the clip to do the pin trick. I would buy new + a cheap hacking dongle kit which seem to sell for between $7 - 20. There are plenty of youtube videos on free hacks and the paid ones floating around.
I would follow that, you will have a switch that cant be hacked! Nintendo changed the switch once the news got out that a hardware exploit was possible with the switch. The chip that the exploit effected was switched out or patched. This making the new switches not hackable. So I would get a used one and do some research as to what ones can be hacked.
I know that for me I went with a switch that I was part of a bundle and I knew it was hackable, i went with the Mario odyssey bundle, with the all red controllers, you can go a different way if you choose. There are sites that you can look up the serial number and that will tell you if its hackable.