Fortigate Demo version

Fortinet, as far as I understand, do not sell directly, only through resellers, which are to be found in any part of the World. So, I guess, if you search Google for your location Fortinet Account Manager and contact them, they will be able to assist. 

Fortinet do have Not For Sale (NFR) and Demo licenses/units, usually sold for 0 or much lower price  to existing partners. But again, you will have to contact your regional account manager. 

If you mean to just see a demo version of Fortigate, then you can do it right here (read-only access): https://fortigate.fortidemo.com/  user/pass: demo/demo

Or download, after registering for free, the Fortigate VM 15 days trial version at support.fortinet.com, there are limitations in this version though - https://yurisk.info/2021/02/28/fortigate-vm-evaluation-license-15-days-limitations/ 

you can buy fortigate nfr's as reseller.