Anyone have a set of basic firewall hardening commands I can put into the routerOS?
You're more than welcome to try to harden the firewall. But here is my 5 cents worth of advice: if your MT device (you didn't tell which one you're using) comes with default setup which features decently long list of firewall rules (around 5 rules for chain=input and 6 rules for chain=forward), then it's likely that default firewall is pretty sound. In this case I recommend you to build on default, but first understand it thoroughly (e.g. what does in-interface-list=WAN actually mean).
Many "firewall hardening recipes" add "port scanning detection" which usually don't add any security to the system. Many "make your firewall safe" actually make it worse due to following "block the forbidden" concept instead of using "pass the allowed" concept. Etc.
MT also provides a document with some recipes to harden the firewall ... but even those rules don't add to security of default firewall.
What many users do is they add rules (because they need to allow some services) and they often f**k up the firewall because they add rules in wrong place (rules are evaluated in order from top to bottom) or the rules are plain wrong or ...
The "best" thing some users do is to add logging rules (to log forbidden traffic) and then they become upset due to excessive logs ... the reality of internet is that there will always be a lot of probing, trying to find a vulnerable device. If firewall is "water tight", then logging is not necessary.
I'd like to point to another thing: IPv6 firewall. IPv6 is a pretty different beast than IPv4 so one should not try to "map IPv4 rules to IPv6", this won't work well. Also: in ROS v6, IPv6 is an optional thing. If IPv6 is enabled, the default rules are not applied (default is only applied when device config is reset to factory defaults and only defaults for modules installed and enabled get applied). So it's crucial to apply some IPv6 firewall rules immediately after enabling it ... it's possible to "hand apply defaults" by copy-pasting defaults (which are displayed by command
/system default-configuration print inside a really wide terminal window).