@ml There are more than one wagon and the train (and the station) is clearly marked for which ones are for wheelchairs and which ones are primarily for bikes. It's in general very nicely thought out, already before the train arrives there is a display showing roughly where the bike entrance and wheelchair entrance will be so you can place yourself accordingly. In practice it doesn't always work out, the train might stop 50 meters further away than was intended.

The trains might be nicely prepared for the wheelchairs but the stations don't always have elevators and that limits the amount of wheelchairs quite a bit I'm afraid. Not everyone can carry their wheelchair up 47 steep steps... The accessibility still needs a lot of work in certain parts of Germany.

My favourite train changes wagons over the summer for the tourists, the whole train is 50/50 bike/passenger split in the middle. Every wagon can take 10 bikes but you can squeeze in the double. However, 30 cm step to the platform.