How can I put all FAQs in one page in Magento 2?

As you concern, the default of Magento 2 does not support Q&A function, so store owners cannot collect and show all frequently asked questions in one place for customer convenience. However, understanding this drawback of the default, there are many Magento 2 FAQs extension released to solve this issue.
Magento 2 FAQs Extension allows admin to create and customize FAQs page in order to increase customization and interaction with customers. Here are useful feature of Magento 2 FAQs extension:

• Show FAQs on product page and submit questions easily
• Be able to create and show FAQs in their own pages
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• Enable to create and show FAQs categories
• Configure to show most recent and related FAQs
• Enable to search questions and answers based on tags and keywords
• Vote button for answers as helpful or unhelpful as wish

You can easily solve your customers doubts with the help of FAQ Manager Magento 2 Extension.
It has all basic features required for any FAQ extension like fully responsive, attractive accordian style display for faq's, category management and many more. Also the most useful feature is it supports video FAQs also. So it provides more user friendly interface.

Thanks for the Post. You can also check this FAQ Module. The overview of the product are as follows:
> Question rating allows customers to evaluate the usefulness
> SEO-friendly tools for better content visibility
> Viewing stats available to admin at backend
> User-friendly layout allows easy navigation at frontend
> Question categories split questions by topic