You can use a ledger with the DEFI. It is limited to the RUNE side... but you can still enter any pool with only RUNE and only pay RUNE gas. It is actually pretty incredible... you can gain exposure to any project on THORChain, from you Ledger with only RUNE.

Now with Synths out, you can also purchase them with RUNE from your ledger.

You can read about Ledger and THORCHAIN here