My .htaccess was ill-advised. It reset my PHP back to their baseline, 7.something. I believe Chillidog has a cPanel feature for adjusting .htaccess that should be used instead of uploading anything. I’m editing my post to redact the .htaccess I posted.
I di years ago thats why I went to Chiilidog and Greg helped me set up and transfer all my sites and I had very little downtime. I suggest you do the less important ones first and work up to the most important ones last and you will have very little downtime. The only wait is for the DNS to transfer over.