Connect to PSQL:
docker exec -it $(docker ps -a -q -f "name=postgres_1") psql -U postgres -d btcpayservermainnet
set search_path to "BTCPayServer.Plugins.LNbank";
Then you can see wallets:
select * from "Wallets";
Note WalletId. Then for each walletid you want to settle (replace XXXXXXXXXXX with wallet id):
select sum("AmountSettled") from "Transactions" where "WalletId"='XXXXXXXXXXX';
The amount will be in milisatoshis. Divide by 1000 to have it in sats.