https://checkgzipcompression.com shows a red warning saying my site is NOT compatible with IPv6.
Q1. Will this result in "penalties" either by google or other pagespeed related bottlenecks?
Q2. Is it possible (and if yes how) to enable ipv6 compatibility on a shared hosting with php7/.htaccess and further not much to set? Thanks!
A1: yes, there are page speed limits, also stability and reachability problems, by people forced to use NAT or CGNAT,
Google doesn't care, there is no penalty, Google still honors content
A2: No, it is some layers deeper, if you use ip-based restrictions in your .htacces file, you have to check them, when your hoster enables IPv6, if you process ip-adresses within your php-app you should aware that IPv6-addresses are different