I also asked myself this question and asked customer service directly in the app. Yes, there are spare parts.
The official answer:
Hello,

Thank you for contacting us. You can purchase the "extension bar" separately from our customer service team. Unfortunately, it is not possible to connect two extension rods together. You can order other spare parts and wearing parts on our official Swiss website.

Free service number:
+49 800 000 1747
(Monday-Friday
9:00-21:00
Saturday-Sunday
9:00-18:00)
E-Mail:
aftersales@dreame.tech

Thank you for your support and understanding.