As @PhilipDAth says you need to look at the details for all the endpoints you are using, even if the name/parameters are the same, do not just assume it works exactly the same, the v1 responses can be far richer (and continue to evolve).
The link @KH posted is probably the best way to speed up identifying the v0-v1 mapping.
Then use the respective endpoint pages to compare v0 with v1...
https://developer.cisco.com/meraki/api-v0/overview/
https://developer.cisco.com/meraki/api-v1/overview/
With v1 there are many more endpoints, in particular there may be v1 ways to get org-wide info that would have required iterating over networks in v0. I would take some time to look at the full set of v1 endpoints and see what opportunity there is to improve rather than simply replicate a v0 approach in v1.
You don't mention what environment your customer is using, the Meraki Python library is good, it handles a lot of the low-level work for you and tracks API updates pretty closely...
https://github.com/meraki/dashboard-api-python/blob/main/README.md
Also there's the official Ansible collection...
https://blogs.cisco.com/developer/merakiansiblecollectio01