Magento 2.3 product availability

Product Availability How to get it
Magento Open Source 2.3.0 GA Available now Composer
Magento Commerce 2.3.0 GA Available now Composer

For partners and existing customers only
Magento Commerce Cloud Tools (aka ECE-Tools) Available now Composer
PWA Studio Available now as an open source initiative.

Commerce Cloud deployment planned in early 2019. Regular releases independent of Magento will extend basic Venia PWA storefront and Studio development tools. Current roadmap updated here.
Documentation and GitHub
Magento Payments Early access open for US-based merchants

Regional availability expected in Q1 2019
Request access

Self-service onboarding from Magento.com
Magento Shipping Available now Merchants on Magento 2.2.2+ can use the onboarding process
Page Builder Available now for early adopters

General availability expected in early 2019
Bundled with Magento Commerce 2.3.x
Amazon Sales Channel Early access closed

Regional availability expected in first half of 2019 (US, Canada, Mexico, Australia)

Global availability expected in second half of 2019
N/A

Magento Marketplace
Google Ad Channel Early access TBD

General availability expected in first half of 2019
TBD

Magento Marketplace