Fable: cross-buy and cross-save
One purchase covers Xbox and PC. PS5 is a separate listing, and no source states cross-save.
Does Fable have cross-buy?
Partly
Xbox console and Windows PC share one purchase through Xbox Play Anywhere. The PS5 version is listed separately on the PlayStation Store.
Does Fable have cross-save?
Unconfirmed
Neither Xbox's page nor the PlayStation listing mentions cross-save.
Source
Buy Fable once and play on XBOX console and PC for no additional cost.
Limits of this entry
The Xbox page links Steam as a store but does not say whether a Steam copy counts as a Play Anywhere purchase. The PS5 date comes from the PlayStation Store listing, which I read through a search summary.