Best I have done is around 1.5M free sats in a year and that includes sats back from a visa debit card and sats back from buying gift cards from the Bitcoin company.

Best of luck. Besides a sats rewards visa, if you can put all your monthly expenses on it and get 2% in sats back, SN will be your best option to stack "free sats". You might be able to do 1M just from SN if you put the work in.