@ramses-sevilla
Ok, you asked for it.
This could be used on another system, with shell access and the wget command :
https://forum.netgate.com/topic/123405/get-certificates-from-pfsense-cert-manager-using-linux-commandline/4?_=1615276186290
pfSense doesn't have 'wget', but has curl. You should be able get the (html) page, using sed and awk to filter our the certificates, and text like "Valid Until:" etc.
pfSense is a GUI firewall. There is no straightforward command command do what you want.
If the certs where stored some where in the file system, you could use the openssl command and option to get the all the date info from a cert.