Security Professional Seeks SASE Vendor Recommendations for Company-Wide Transformation

I'm the only security person at my company and I have to recommend a SASE vendor by Friday. The company has 800 employees across 12 offices on three continents, with most staff working remotely. The current network relies on MPLS for site connectivity, a split-tunnel VPN for remote users, and an undocumented patchwork of security tools. The author is tasked with consolidating the network and security infrastructure into a SASE solution, despite limited experience with large-scale transformations. They seek insights on unexpected deployment challenges and vendor questions from those with prior experience.