Suppose that my company uses Scrum framework for develop different complex products and our Product Owner needs go for vacation (3 weeks) in the middle of project (the vacations cannot be cancelled because include ticket flights):
1) Scrum allow that assign some Proxy resource in order to reeplace it during their absence?
2) If #1 is Yes, The person to replace it could be a team member of the Development Team?
If you have 1 month sprints, and if the PO is available for Sprint Planning before going on vacation for 3 weeks and is also available for the Review and Retrospective upon his or her return, you may not need a proxy.
Otherwise, yes a proxy could be found from within the Development Team. Note that this proxy would require the authority to negotiate a Sprint Backlog and also to potentially release an increment.
The PO's absence could therefore be an opportunity to pay off any outstanding technical debt.