The latest edition of Tabletop Gaming magazine (March 2021) has free Digimon promo cards for the new Digimon card game!
You get all six cards in the magazine Agumon, Gabumon, Biyomon, Gatomon, Patamon, and Gomamon which is nice.
This is a UK-based magazine so you may be able to find it online if you don’t live in the UK. It is being sold for £6.99.
Edit: Click here if you are from outside the UK and are wanting to buy the magazine!