At some point in the not too distant future we should be able to design themes for WP in Blocs and export without a lot of the bloat typically associated with page builders like Elementor. That should deliver fast performance with reduced chance of conflicts.
As a very real example, a friend of mine is a photographer with a WP site built with some page builder and it goes offline every week with one problem or another requiring maintenance. Earlier today it had too many redirects, which has now been fixed but still no images at time of writing.
Norm explained it pretty well here General Question - Wordpress/Blocs pros and cons - #10 by Norm
Ecwid and WooCommerce both have pros and cons. In this instance the client wants the flexibility to make changes in future, potentially adding more pages etc, so WordPress seems like the logical, albeit reluctant solution from my perspective. I haven’t told the client I stopped eating meat last year, but the cat should be sorted until August.