These are just two mechanics I want to note here before they are lost in notebooks.
1. Soft class
There is a single pool for Armour, Utility and Stamina. It is somewhat abstract, stingy and very difficult to level up, so there always a trade-off of some kind between these three.
Armour allows to wear heaver armour, which in this setup, would provide useful damage absorption.
Utility is both for useful on-hand tools, such as wands and potions, but also for spells/active martial masteries and so on.
Stamina is for better movement (including such things as climbing), wielding bigger/more demanding/more complicated weapons and more efficient shields, get-out-of-jail-free-card-maybe dodge.
Idea with slots for mental as well as physical resources isn't new, but I want to see if combining everything in the same small pile and allowing for soft split between these three – which would be, ideally, adjustable after a long rest – takes care of mechanics which are usually hard-coded into the class progression or demand permanent commitment such as feats.
So far, it will probably look like "you have nine dots, if you want medium armour proficiency it is six out of them, you have three left for everything else, where do they go?"
At least one drawback I see is that for tabletop it might cause some unnecessary bookkeeping. Things once marked on paper prefer to stay this way, and adjustable-freely it might cause some mess, not mentioning players taking time and fiddling with it each long rest. Maybe fixed with some kind of "rebirth", Rosaria/Rennala way for restatting, so it is still available, just not too freely to avoid headaches.
Second, of course, would be to avoid an exploit where one just puts everything in one of the three. Here I think Stamina is the most potentially troublemaking, as mobility, initiative and speed always are DnD weaker spots, mechanically.
Levelling up this pool should be possible but prohibitively expensive, so there would be another tradeoff with levelling stats/other abilities or getting something else useful.
2. Contacts / External specialists
This was initially used for Ghostwire Rain and I think it might be useful for other games. The purpose is to get on-fly Contact that might offer some external expertise for a player character stuck with a need of one without 1) spending time predefining a person that might not come to play 2) spending too much time doing the same on-fly.
Each character has one* unspecified contact they can draw upon at any moment by specifying them. Player tells the name and, briefly, what is a common history between their character and that person; DM specifies personality and fills other gaps as needed. Such contacts are acquaintances or at some arms length away, not close friends, and reflect 'I happen to know the person' kind of familiarity; contacts and allies obtained naturally by adventuring, role-playing and other specific effort are beyond this system.
(*) or one per adventure, if the game is in urban kind of environment or players are in a line of work that involves a lot of social or investigative activities.
Regardless of what they do, Contacts come in three aspects: Cheap, Good and Fast.
Contacts who have only one aspect (i.e. cheap but neither good nor fast) are easily available. It isn't a challenge to find somebody like that.
Contacts who are all three (i.e. cheap and good and fast) are always in demand by everybody else around them and are almost impossible to reach and enlist for service; they are fully booked at best and fully booked for next three years at worst.
So the Contact in question has two aspects out of three; player tells DM which are those. For example, they want Bluebird the Hacker be good (obviously) and cheap (because PCs don't have much money) but not fast (there is still a plenty of time before bombs go out).
Then there is a roll to see if this contact is available; such roll is challenging but not too difficult. Depending on the system, the roll might be helped by background (it is easier to know a gossip-mongering noble if one's background is a courtier) or some other aspect of the character, such as high skill.
Critical failure on such roll will take one aspect (player's choice) off the contact: i.e. Bluebird the Hacker is still good but not as cheap as one expected. Failure will mean some minor upset such as their negative aspect will a bit be more prominent this time, so Bluebird the Hacker might take some extra time this time in addition to be slow as usual. Critical success will update the Contact to all three at once, i.e. Bluebird the Hacker this time works fast in addition to good and cheap.
Contacts are usually not willing to do anything obviously illegal, even in criminal underground as the paranoia that one might be set up or sold out is ever present.
Once specified in such way, Contact remains permanent if player desires so. I think if the game uses a downtime system there should be an option of maintaining / updating / dropping Contacts for people who just want to have this kind of network.