This is impossible on several levels. Most Chinese citizens are 100% convinced that Taiwan is a breakaway province and the mere idea of its independence is extremely offensive. Even if Xi himself were amenable to the idea of a treaty (which he is not — rather, he sees the “reclamation” of Taiwan as his opportunity to write himself into the history books), his government would not be so foolish as to shoot itself in the head.
And your assessment is right. It is unimaginable for any leader of CCP to grant independent state to Taiwan. He would be buried by party members and mainland Chinese.
This sort of treaty still needs to be approved by China's parliament. Though in most cases it is a just formality for parliament to approve any treaties but when it comes to a treaty that grants independence of Taiwan, vast majority of parliament members would object it.
And please be aware that Chinese people do go to street. Recent demonstrations in multiple cities and universities against endless covid lock downs proved it.
Edit: and thank you for your first-hand input on Taiwan.