What are going to be the unobtainable achievements?

[Blue 03]

What are going to be all the unobtainable achievements? Any tips to get them as well? I think some you'll have to be playing during a specific event. Another random question, if my friend were to have bought the standard edition of the game, can he still buy the LEGO and Fortune Island expansion upgrade in-game before it gets delisted?

[Szymon257]

Time limited achivements are listed here https://forza.net/news/forza-horizon-4-delisting
And no, you can't buy dlc after game get delisted.