I see.  Strike now does have a Bitcoin wallet (account) as well as the USD wallet (account), but that doesn't interact with lightning.  There is a Send button so I can pay bitcoin on-chain, but there is no Receive / Deposit for bitcoin, as far as I can see.  You can buy (and sell) BTC from this wallet (account), so at least you can self-custody your coins.

But for LN payments, you are correct -- incoming sats (via LN) will be added to the USD balance, and outgoing sats (via LN) are subtracted from the USD balance.

For internal / account-to-account (i.e., send to another Strike user), the amount is in dollars only.

ClubAlpaca

bitcoin

The TRUTH about BITCOIN in EL SALVADOR 🇸🇻 (Bitcoin Beach Tour)

faithandcredit

Strike doesen't transact in lightning like most wallets. Strike automatically converts bitcoin to and from the local currency into and out of lightning. This transacting in dollars or the local currency was against the initial conditions for the donation that started bitcoin beach in the first place.