Embed commenting possibility similar to Discus (Commento, jointcomments, getreplybox)

I want to open a page so that readers can add their comments directly through the browser. I have seen https://github.com/pschmitt/pico_disqus but would like a free alternative with no adds.

All the functions mentioned have a js-script.
Getreplybox is like this

Place the following code where you’d like ReplyBox to load:

Place the following code before the closing tag:

How can I do that in PicoCMS?

If you wanna include some JavaScript you can do so by editing your custom theme. First create a custom theme (e.g. by copying the default theme) and edit your .twig templates (e.g. nextcloud/data/appdata_*/cms_pico/themes/my_theme/index.twig) accordingly, for example by adding the JavaScript right below {{ content }}.

Thanks. So I can copy the folder /var/www/nextcloud/apps/cms_pico/appdata/themes/default/
to nextcloud/data/appdata_*/cms_pico/themes/ and rename the folder /my_theme and work out from there?
I will try that and report back. It seems to be a solution.

I want to use this commenting service
https://getreplybox.com/docs/getting-started-universal-code

I have made a custom theme and inserted

<script>
window.replybox = {
site: 'XXXXXXXX',
};
</script>

after

<div id="main" role="main">
<div class="container">
{{ content }}

and added

<script src="https://cdn.getreplybox.com/js/embed.js"></script>

at the end before
</body>

I have inserted <div id="replybox"></div>
in the index.md file.

But the replybox does not appear
Anything wrong?