Other open-source hardware wallets (altcoin wallet, not bitcoin only) have few users and less attention, making them less secure.
Having less attention doesn't necessarily make you less secure. In fact it may be the exact opposite.
You may be right. I found user reviews of different wallets on the bitbox website. see
https://bitbox.swiss/bitbox02/#compare and
https://www.trustpilot.com/review/bitbox.swissI compared several kinds of wallets and recorded the theft situation myself, as follows:
Trezor, User score: 3.5, Number of reviews: 405, Number of stolen users: 12, Some details: Robert in AU, 160,000$ stolen; Curtis in US, 100,000$ stolen; Donald in US, 60,000$ stolen; Voodoo in AU, 0.4BTC stolen.
Ledger, User score: 2.8, Number of reviews: 1559, Number of stolen users: 12, Some details: Di in IT, 1 eth stolen; Ale in AU, 0.33BTC stolen.
Keepkey, User score: 2.4, Number of reviews: 290, Number of stolen users: 1, Some details: Gennady, 5000$ stolen.
BitBox, User score: 4.9, Number of reviews: 547, Number of stolen users: None
Keystone, User score: 4.2, Number of reviews: 47, Number of stolen users: None
Onekey, User score: 3.5, Number of reviews: 56, Number of stolen users: None