The automation tool that would best achieve this is to create a page action set to tag prospects as having viewed it and add them to a list. A page action is a feature that allows you to track and act on the behavior of prospects who visit specific pages on your website, such as your pricing page, product page, or thank you page. You can use page actions to perform actions on the prospects who visit the page, such as adding them to a list, assigning them to a user, or changing their field values. You can also use page actions to customize the content or layout of the page based on the prospect's attributes or behaviors2. To create a page action, you need to specify the URL of the page that you want to track, and the actions that you want to execute when a prospect visits the page. For example, you can create a page action that matches the URL of your pricing page, and tags the prospect as having viewed it and adds them to a list of pricing page visitors.

Explanation
The only required field for a record in Salesforce to be synced or created as a prospect record in Marketing Cloud Account Engagement is the email address. Marketing Cloud Account Engagement uses the email address as the unique identifier for prospects, so it is mandatory for any record to sync between the two platforms. Other fields, such as name, company, or phone, are optional and can be mapped between Marketing Cloud Account Engagement and Salesforce, but they are not required for the sync to happen. For more details
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Explanation
A prospect is automatically removed from future email sends when they either hard bounce or soft bounce five times. A hard bounce occurs when an email is permanently rejected by the recipient's server, usually because the email address is invalid, non-existent, or blocked. A soft bounce occurs when an email is temporarily rejected by the recipient's server, usually because the mailbox is full, the server is down, or the message is too large. A hard bounce indicates that the email address is no longer valid and should be removed from your list. A soft bounce indicates that the email address may still be valid, but there is a temporary issue that prevents the delivery. However, after five soft bounces, Marketing Cloud Account Engagement will mark the prospect as undeliverable and stop sending emails to them

A completion action on a custom redirect will be triggered when an existing prospect clicks on the custom redirect. A custom redirect is a trackable link that can be used to measure the engagement of prospects with external content, such as a website, a PDF, or a video. A completion action is an automated task that can be performed after a prospect takes a certain action, such as clicking on a custom redirect. Completion actions for custom redirects will only apply to existing prospects, meaning prospects who have already been identified by Marketing Cloud Account Engagement through a form, a landing page, or an email4.
References: Marketing Cloud Account Engagement Custom Redirects