Yes, you can buy BTC on https://getalby.com/topup from MoonPay and have it directly sent to your Alby account.
You can buy sats on Alby with a prepaid card?? Is it KYC’d?
You can certainly try a p2p platform like nostr:npub1p2psats79rypr8lpnl9t5qdekfp700x660qsgw284xvq4s09lqrqqk3m82 and set your payment method to “prepaid visa” etc
Not sure of exchanges/money transmitters who accept those cards but certainly would love to know too