THIS!!! This is the best advice I have found on this topic. Archiving affects SEO without setting up URL Redirects (which can be cumbersome with large quantity of archived products to manage). Too many URL Redirects over time is also not good for your site performance from what I understand.
However, when I test this out you still get a 404 if the product was previously searched and is in a customer’s browser history…
But to basically ‘unpublish’ the products removes them from your customer user experience but keeps the product SEO intact.

