I am not very much familiar with hardware wallets, but I've always believe ledger and trezor were the best of them all until recently when alot got revealed about ledger, and then, the issue of them not being open source came up, Trezor  on the other hand have been doing quite well but several people believe they have some kind of privacy  issue which originated from Wasabi's coinjoin services integrated into the wallet..

Right now, I can't point to a particular hardware wallet I can vouch for as open source, but one which I am personally looking forward to using is Arculus from chainge finance, Arculus is a hardware which I believe have not started shipping out, but from all I've read about it, it may likely be a great choice, though like I said , I've not confirmed if the wallet is open source or not.