Question about Xiaomi 15 Ultra

There are some third-party bloatware apps, but they can be completely removed. As far as I know, Chrome cannot be removed from any device (regardless of brand) without root access and neither can most other Google apps. Most (possibly all) MI apps can also be uninstalled, but I would be careful with system-critical apps. Regarding adverts: I haven't seen a single app-integrated advert so far, so I don't think there are any.
Hope this was helpful, best regards.

you can safely remove all bloatware. Also Mi-stuff - should you miss something, you can always download the corr. apps

No advertising. No problem with bloatware.