Forza Horizon 5 cross save between PC game pass and Steam

No.

The Steam and XBox versions are totally different...if you want to play on both platforms, you need to buy it on both platforms.

Also, far as I am aware, there is no cross-save between Steam and XBox either:

https://support.forzamotorsport.net...803-Forza-Horizon-5-Cross-Play-and-Cross-Save

You can't as you did everything on steam

For the most part, cross-save support is present in Forza Horizon 5. The only exception to this rule is for those PC players who are playing through Steam. Steam players do not have cross-save support on their version of the game.Nov 8, 2021

This is the price you pay for switching platforms

Well it is cross save compatible just not in the way you mentioned

Play anywhere title only apply to Xbox platform not steam

Also cross saves usually only apply to same platforms with the rare exceptiOns of certain titles

Steam saves are steam saves and Xbox one's are encrypted

However.achievements do carry over

'Forza Horizon 5 will support cross-play and cross-save across Xbox Series X|S, Xbox One, Windows 10 PC, and Xbox Cloud Gaming.
Steam will have support for cross-play, but cross-save with Xbox is not supported.

Depends on the game, if hte game is cross-play the save files are transferred between PC and Xbox. Game that allow Cros-play for example are: Halo MCC, Forza Horizon 4 and Gears of War 5

Forza Horizon 5 does NOT have any announced or planned cross-progression from Forza Horizon 4. Aside from Forza Horizon 1 (which did had loyalty rewards for Forza Motorsport titles), there has never been cross-progression for Forza Horizon titles. You always had to start fresh with each game.

And about Forza Horizon 4: the lack of possibility to use the same save between Steam and Microsoft Store comes from the technical point of the each game. Both use a wholly different methods of saving which is far too much work to make them co-operate, ESPECIALLY considering that Forza Horizon 4 is way past its' prime.