If I had to guess, probably not for feature phones.

Since every user has a Lightning address (their [phone number]@8333.mobi and optionally, [username]@8333.mobi, thus anyone can send from to a Machankura user, including from non-custodial LN wallets.

For receiving, for a non-custodial wallet, I suppose the service could add a way you could provide an LNURL-Pay so then any payments received at your [phone number]@8333.mobi just get forwarded (sent again) to your own node. There's custody by 8333.mobi, but for just a short moment till the payment is forwarded.

I don't think they've decided how best to accommodate this, but I did heat that topic discussed on the Twitter spaces for this.