There's a minor problem in the rules UI: Without any interface rules (on MyLAN) the message "No MyLAN rules have been defined. All incoming connections on this interface will be blocked until you add a pass rule. Exceptions for automatically generated or floating rules may apply." is shown. To be perfectly correct, the message should also mention group rules. Actually, I think the message should not pop up at all. Block by default is fundamental to OPNsense.
Its pretty much the same as the old rules banner:
https://github.com/opnsense/plugins/blob/7c8cc9544b9cbe36d428aece439565167b6841c5/net/firewall-legacy/src/www/firewall_rules.php#L696-L698
That group is missing is valid.
That the banner shouldn't show at all, that's taste I suppose.
Here you go, group added:
https://github.com/opnsense/core/commit/9838676f3295112cae351bf9d88b22c730fd2079
Thanks.