I’ve about a dozen Google sites which are just an embedded Google form with a custom script at the back.
I tried the conversion tool on a dummy site and it opened a Google doc. I am not sure how an HTML page with embedded Google form with a script will be converted to new Sites.
GST replaces both central and state taxes. States' share is 50% of GST (CGST and SGST). Only alcohol, petroleum and electricity is kept out of GST, which are still taxed at state level.