No campaign transfer, but a save-data reward
The official Xbox demo description embedded with Capcom’s developer interview says demo progress cannot continue in the base game. It separately identifies a Kubi Akari charm reward for players with demo save data. These are two different systems: a reward can recognize a save without importing its campaign state.
Capcom’s demo announcement describes a sample designed to teach the combat. Treat it as practice and a suitability check, not an early start on your final equipment progression.
What to keep before moving to the full game
Keep the demo’s save data until you have checked the full game’s reward availability. Do not delete saves just to reclaim the space used by the application. Application files and player saves are different things.
On PC, use the same intended storefront and account for the test where possible. The reviewed sources do not establish a transfer between Steam, Xbox and other store accounts. Do not assume an Xbox demo save grants a Steam entitlement.
Do not grind on an unsupported promise
There is no evidence here that extra demo currency, a faster clear, or repeated boss wins become a larger campaign head start. Spend your demo time on recognizing attacks and deciding whether the performance works for you.
If the charm is missing, first confirm which account owns the full game and whether the demo save still exists. Use current official support guidance instead of replacing files with someone else’s save or downloading a supposed reward unlocker.