About Ledger Nano, it can be operated with open source wallets also like electrum, but only what I do not like about the wallet is the close source microchip used to generate and store seed phrase which is close souce, so if their is vulnerability included into the microchip like that can pre-generate the seed phrase, people will not know, but the company still maintain good reputation till today.
Indeed they do, and personally I'm not too concerned that Ledger is secretly keeping all of its users' seed phrases in some database somewhere in order to perpetrate some massive scam in the future. I don't like that the code is closed-source either, but I'm old school and tend to need to have a little trust in things like this--but I can see where it would make some people very uncomfortable.
You really can't be sure especially with hardware wallets like Safepal and Ledger that are totally closed source and protected with various NDA agreements,
Safepal I'm not so sure about, and that's mostly because I'm not as familiar with them as I am with Ledger. I had to take a look at their website, and they've only been around since the beginning of 2018--thus they don't have quite as much of an established track record as Trezor and Ledger do. They could be completely above-board, but I wouldn't risk it if I were looking for a HW wallet (which I'm not). I'd definitely stick to the biggest and most reputable names in the industry.