Running two WordPress installations for the same domain vs. Multisite

Hi, let me put you in context.

I am building a website on which I want to use one specific feature from one Theme on the Homepage but I want to run a totally different theme for the rest of the pages.

I was thinking about two options to do that:

1. Having two WordPress installations: one for the homepage and another for the rest of the website allocated on a subfolder. Having something like this:
– https://www.mysite.com (For index aka:homepage)
– https://www.mysite.com/site/… (For all the other pages)

2. Running a multisite WordPress with subfolders setup to do exactly the same.

My questions here are:

Which one would make more sense on an optimization level?
Will this impact my SEO ranking badly? I have thought on this one and I think not so much as they will appear to be part of the same domain right?

Thanks for your help.