We Never See Nothing

I just bought a nano ledger X and the day after I see this post:

https://reddit.com/r/CryptoCurrency/comments/hnw01n/kraken_security_labs_identifies_supply_chain/

That made me a bit scared of putting my funds on the new ledger or keeping it on the ones I already have.

1. How do people who own hundrets or thousands of bitcoin keep it safe? Their own hardware wallet or ledger or trezor or any other wallet produced just for this purpose?
2. Concerning this post I linked to: I’m not sure if what they’re saying is that if someone opened my ledger, did something with the hardware and closed it again, if they would be able to get the funds FROM my ledger. Would that be possible in any way? Or are they more talking about them adding malware to the ledger which would get on my computer but couldn’t actually reach my private key?
3. Generally, if someone got their hands on my ledger before I got it. I open it, everything looks normal on setup, no words already written down on my recovery sheet. Basically I, as the user, know what I’m doing and to me everything looks normal. Is there any way at all for someone to have done something to my ledger that would allow them to get my private keys? Even though everything looks perfectly fine.

Edit: Corrected some errors. Third question is itching the most.

I hope I can get some answers to those quesions that I will be able to verify on my new ledger nano x. I have been into bitcoin since the run in 2017 and have been using the nano s since then so I know pretty well what to look for and how bitcoin works in general. Thank you for providing any additional information if you have any.