oca-website/odoo-bringout-oca-website-website_whatsapp/website_whatsapp/templates/website.xml

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
    <template id="layout" name="Floating WhatsApp Icon" inherit_id="website.layout">
        <xpath expr="//div[@id='wrapwrap']" position="after">
            <t t-set="extra_info" t-value="''" />
            <t
                t-if="website.whatsapp_text"
                t-set="extra_info"
                t-value="website.whatsapp_text"
            />
            <t
                t-if="website.whatsapp_track_url"
                t-set="extra_info"
                t-value="website._get_track_url_message(request.httprequest.full_path)"
            /><!-- %0A newline -->
            <div t-if="website.whatsapp_number" class="whatsapp_icon">
                <a
                    target="_blank"
                    t-attf-href="https://api.whatsapp.com/send?phone={{website.whatsapp_number}}&amp;text={{extra_info}}"
                    title="WhatsApp Floating Icon"
                >
                <i class="fa fa-whatsapp" />
            </a>
            </div>

        </xpath>
    </template>
</odoo>