The total time to complete the mailbox/public folder move depends on the total number of mailboxes/public folder selected, the size of the mailboxes/public folder, the properties of the MRSProxy, system performance, network performance, and other back-end tasks that are running during migration time. I can't calculate the migration time, but we could refer to the following document to improve it:
Performance factors and best practices for hybrid migrations | Microsoft Learn
Before you begin the public folder migration, if any single public folder in your organization is larger than 25 GB, we recommend that you delete content from that folder to make it smaller, or divide the public folder's content into multiple, smaller public folders. Note that the 25 GB limit cited here only applies to the public folder and not to any child or sub-folders the folder in question may have. If neither option is feasible, we recommend that you do not move your public folders to Exchange Online.
Batch migrate Exchange Server public folders to Microsoft 365 or Office 365 | Microsoft Learn
In addition, the normal way is to migrate public folders to public folders, but you would like to migrate public folders to user mailbox? For this situation, you could consider Outlook PST Import/Export feature.
Batch migrate Exchange Server public folders to Microsoft 365 or Office 365 | Microsoft Learn
see Migrate Public Folders to Office 365 by using Outlook PST export