Anything is possible if you've got the time and resources but if you are looking for a dependable and cost effective solution to use CiviCRM on a website, you are going to have to use Drupal, Wordpress or Joomla.
I would find out why the client wants to use Craft as opposed to Drupal. More likely than not it's because their Drupal site is poorly configured and they aren't getting the most out of it. My plan would be to do a deep dive with the client to assess their use of the site, how the site is configured and come up with a plan to make it work for them.
You could put CiviCRM on a headless Drupal instance and build an API endpoint to communicate with the Craft site but that seems like an awful lot of work for very little return.