Quote from: The Cryptovator on Today at 08:33:06 PM

So with a secure chip, can we trust that the wallet is safe and doesn't have a chance of being drained by the manufacturer?

Yes, Trezor 3 Safe is using open source secure element model Infineon OPTIGA Trust M, and that can be verified.
Most of the other brands are using secure elements that are closed source.

Quote from: The Cryptovator on Today at 08:33:06 PM

I need a multi-currency hardware wallet that is secure, smart, and open-source, price really doesn't matter. One of my choices is Keystone due to their wallet design, especially the fingerprint system. But it seems they used three secure chips, and I am not much aware of whether the manufacturer can drain wallets somehow through the secure chips.

Keystone is sadly still not open source wallet, but they promised to release source code in November, so let's see.
I heard several complains about them, but compared to other available hardware wallets they are not so bad.

Quote from: The Cryptovator on Today at 08:33:06 PM

Please suggest details and why you think I should buy this. Please don't send the list to compare wallet, just suggest best one.

Based on what you wrote I think that Trezor 3 Safe is currently best available hardware wallet for you.
It's open source, not expensive and it can support bitcoin with other altcoins.
Note that all wallets have pros and cons, there is not one wallet that is best for everyone.