Ok thanks you very much

Can you please answer these 4 questions :
1- Does Nxfileviewer check confirm if the nsp is completely safe ? I just wanted to confirm.
2. Is this DBI tools safe ? ( people on nh guide discord were telling me not to use dbi or tinfoil because of the source code)
3. I used nh guides so I never used sigpatches like they said in the retry guides. Do I need it especially if I want to use clean nsp games ?
4.They said it is « for Sigpatches
allow your Switch to install and run unofficial NSP files » so Can you explain the reason why I need it if it’s not corrupted files and correct nsp dump ?
Thanks