One-Time GA to Matomo Migration - 1 Account - 6 different webpages

I’m running the latest on-premise build of Matomo and want to bring in everything that still sits inside our Google Analytics property. The goal is a single, comprehensive migration: user behaviour, acquisition, conversion—essentially every hit GA will let us export.

Key points
• Scope: one-time import only; no recurring sync.
• Existing Matomo reports must stay intact, so please configure the importer to merge the incoming GA history with what’s already there.
• Environment: self-hosted Matomo (latest stable), full server and database access available.
• Tools: you may rely on the official Google Analytics Data Export API, python-matomo-importer, or your preferred scripting approach as long as it works securely on-prem.
• Deliverables:
– Complete GA dataset migrated and visible in Matomo’s standard reports.
– Written steps or script so I can reproduce the process if needed.
– Brief verification checklist confirming totals match between GA and Matomo for a few spot-checked periods.

If you’ve handled GA-to-Matomo moves before, especially on self-hosted stacks, I’d love to hear how you’ll tackle the merge without data loss or duplication.