If your fund is big, I don't see how you can not afford to spend money for purchasing a second hardware wallet that is used only for altcoin storage.
It makes no sense to buy a second hardware wallet, you can use one Keystone 3 pro. I already wrote earlier that it supports importing three mnemonic phrases at the same time:
I use Keystone 3 pro and practically do not see any alternative options for it, since it supports the import of up to three different mnemonic phrases, so you can allocate Bitcoin to one mnemonic, a wallet with the Solana ecosystem to another mnemonic, and EVM compatible ones to a third mnemonic. Bitcoin maximalists can use the Bitcoin-only firmware.
Moreover, I read that this is one of the best devices in general for alternative cryptocurrencies, as it is one of the few that support the Cosmos ecosystem.