It's really the best addon to filter groups!
But I feel a lack of regexp support when I need to find a group for a specific key or pvp rating.
For example, I want to find M+2 key party, but the current wow interface will output to me all parties that have 2 in titles, like 22+ or 4x2 farm or 2 last slots or even 123123123123.
It would be great if I can use something like title.match("\b2\b") what will find a group with the exact single number 2 in the description

Sadly not possible anymore. Searching and matching the title was a feature of PGF until BfA. Starting with the Battle for Azeroth Prepatch, the group name and comment is protected by Blizzard and can no longer be evaluated by any addon. I can only speculate about the reasons but assume it was done to stop addons from performing automatic group searches and joins like World Quest Group Finder.