Develop an online store backend on Bitrix

Hello.

It is necessary to develop a backend of an online store on Bitrix according to the finished TK. The PageSpeed of the finished resource should be positive, namely green. It can be assumed that the front (static) fulfills this condition. Requirements are standard: minimum JS, implementation of SEO-requirements (micro-markup, feeds, integrations), WebP, images at least in 3 resolutions, extremely low response from the server, documentation.

It would be good to see examples of implementations with a positive PSI.

Jira, Gitlab, Gitflow, Scrum.