How Moving Sites will Impact our SEO

Hello, guys.

So, we're considering moving away from WordPress to the custom website with some other external CMS.

I have two questions.

1 - Will this change affect your SEO? Considering that we are not changing anything in the sitemap so we're keeping all the exact URLs, meta information, blog content, etc. The only thing that's going to change is the actual CMS and the tech stack of the website.

2 - Which CMS-s would you recommend and why?