Lace is not on mainnet yet. But when it does come and there still isn’t support for 15 word seed phrase, I’d just create a new wallet and send your funds to that one.

Also, just want to make it clear that it’s not a Yoroi wallet you have, it’s just a Cardano wallet that can be opened with any Cardano wallet provider. I currently use Eternl and have had a good experience with it.

Lace is only available on the Pre-prod testnet and currently only supports 24 words. Support for 15 words might be added in future.

I would assume you will be unable to import stuff from the main net (i.e. wallets from different apps, with different seed phrase numbers), only from the lace testnet. That would explain why you can only do 24words.

I signed up for early access. It seems to work, but importing an account only has an option for 24 word seed phrases.

I don’t think Lace is even on mainnet yet right? I think it’s only on the pre-prod network.