I have a eCommerce project and client want website frontend based on Angular 7 and admin panel based on magento 2. Can anyone give me expert advise how to convert complete magento 2 frontend with Angular 7?
In the Magento world many people name this functionality/technology as Headless Magento.
You do not have to convert Magento's frontend architecture to Angular and instead you should completely develop a new app/micro-service for presentation part using Angular and utilise Magento's API to get/post/put/delete data from/to Magento.
You might not find existing API for everything you need to get your task done so you might have to extend/override existing Magento's API and modify it or you have to develop new API for the same.
You can also use a mediation/proxy to communicate to Magento API. You can develop this proxy layer in node, php, python or any other language. Node being faster is preferred.
You can also connect to Magento's database directly from the proxy layer though if you follow this, it will require a lot of work as magento is using EAV model, so there are many tables which is used to store information any entity.
Read more here about Headless Magento.