How in-depth is the theme customisability for developers?


I am a web developer and I have previously made themes for WordPress however I despise working with it as I hate Php. I have been looking for a while now to switch over to GhostCMS for my clients and I would like to know what is possible when developing a theme as I don’t want to learn to use it and develop with it only to then be limited in terms of customizability.

What drew me towards this was how simple and clean the dashboard was unlike WordPress or other CMS’s and its ease of use would be perfect for my clients. If anyone could answer my question I’d be eternally grateful. Anyways here it is.

Can I make any HTML/CSS/JS website on the front end even if it is not a blog but only features a blog element? (I plan to store data like reviews, project posts, etc in the posts area of the dashboard and fetch it into the website)