Thanks for sharing the URL.
The issues seem to be pretty straightforward, let me go through them one by one:
First, the “Only amp-boilerplate and amp-custom ‘style’ tags are allowed and only in the document head” issue:
In your document’s <head>, the following style declaration exists:
<style>
.wp-block-gallery.is-cropped .blocks-gallery-item amp-img > img {
object-fit: cover;
}
</style>
You need to find out where this is coming from and insert that CSS using the amp_post_template_css filter instead of printing it directly.
An example of how this filter works can be found at https://amp-wp.org/documentation/how-the-plugin-works/classic-templates/.
Next up, you are loading a custom JavaScript from Amazon to serve ads. For AMP, you need to replace that <script> with a dedicated <amp-ad>. An example for this could be found here: https://github.com/ampproject/amphtml/blob/master/ads/a9.md
Finally, you are loading a custom JavaScript from your own site (fvm/out/header-d5e81391-1551730066.min.js), containing jQuery and things like Disqus comments. You must not load these on the AMP page at all, as it’s not allowed.
If you want to use Disqus with AMP, you need to use <amp-iframe> to include them. You can find an example provided by Disqus here: https://github.com/disqus/disqus-install-examples/tree/master/google-amp
Generally speaking, it’s a good idea to only enqueue scripts and styles when they are actually used on the page. You can use the is_amp_endpoint() function to check for whether you are on an AMP page or not, and act accordingly. The documentation at https://amp-wp.org/documentation/playbooks/custom-shortcodes-and-widgets/ has some examples of how this works.
You’ll find that there is tons of other helpful information at https://amp-wp.org/documentation/getting-started/, so please take your time to read through the docs.
