Hi @merakiel
Thats a tough one to answer without knowing the use case. What services will your users be using? Are you split tunnelling your traffic so users Internet traffic breaking out locally?
The only sizing principles Meraki provide are below but this is based on Meraki MX hardware, max vpn tunnels and firewall throughput etc
https://meraki.cisco.com/product-collateral/mx-sizing-guide/?file
Darren OConnor | doconnor@resalire.co.uk
https://www.linkedin.com/in/darrenoconnor/
I'm not an employee of Cisco/Meraki. My posts are based on Meraki best practice and what has worked for me in the field.