The most serious attempt to make a tank with some serious AD was Slovakian Moderna, with one or two 20 mm Oerlikon cannons.
People keep bringing this vehicle up, but think about it for a minute... even if one tank is designated air defence for the position spraying 20mm or 30mm cannon shells trying to hit a fast elusive manouverable tiny drone is going to lead to your position and friendly troops being regularly sprayed with cannon ammo... even at close range aligning the sights with where the barrel is actually pointed is actually rather hard because most sights are not intended to be used at very close range.
What you need is a system that can be fitted to any vehicle because every vehicle needs to be protected, but the extent of that protection should not lead to all the vehicles around you being sprayed with lethal cannon fire because they will be firing too and you will get yours back as well.
Something like Arena was brilliant because the munitions were directional but covered a large enough area that they overlapped so it could defend from any single direction attack multiple times.
The Munitions were launched up into the air and directed their fragments directly down meaning they were lethal out to enormous distances like even a rifle calibre round let alone a cannon round.
Part of the irony is camouflage because hiding vehicles in amongst trees or inside buildings or rubble protects you from long range attacks by missiles and guns, but sitting a few metres behind a bush that you can't see through but the enemy has a drone hovering above at a decent height can see you clear as day... and with thermals even on the darkest night so the FPV drone that approaches your position hidden from you behind that bush knows exactly where you are and at the last second pops up and over the bush and straight into you... you might have 3s to realise you are under attack and respond.... good luck with that... where are your guns pointing? That high drone will see and so the FPV operator can skirt around so they are not pointing in the right direction.
Stuff like netting to stop drones and nakidka so they can't find you in the first place plus decoys so they waste time and energy, but make it count... when your decoy goes boom that means their is a drone up high spotting... killing that drone is a much higher priority than any suicide drone.
Having your own drone that can see the approach of an enemy suicide drone from a decent distance is also going to be part of the defence too.
Some sort of EM weapon that fries its electronics and even disables smart fuses would be worth looking at too, but recon devices and systems are more important than ever before, but equally drones reward the aggressive... the best way to stop their drones is to attack attack attack... send in waves of your own drones to chase them into buildings and into bunkers and if someone escapes follow up with other drones.
Having IFF systems for drones is important too because then you can dedicate some of your drones to hunt enemy drones.
The most useful drones to hunt, as I said, was the higher flying optical recon drones that they will use to find targets, though they might also use satellites for that too...
Flying at higher altitudes means you could carry a shotgun like weapon and fly at the target like a WWII fighter... higher flight speeds would be good to cover more airspace and move from one target to the next... obviously critical to distinguish friend from foe...
LIDAR would be best because it gives very precise range information (like a laser range finder) but can be used to scan a large volume of airspace and is not effected by temperature or radar cross section... a stainless steel target would appear the same as the same target made of cardboard or light plastic.
BTW if you want a tank to deal with drones....
Of course with two 30mm cannon each with dual feed systems one feed from each cannon could be HEAP-T as a general purpose round to spread destruction on area targets from both guns at one time, and then one gun can fire APFSDS to take on enemy armour if it appears... one gun would be enough fire power because accuracy is more important that all out high rate of fire in the anti armour role, which leaves one ammo bin in one remaining gun which of course would be air burst 30mm cannon ammo for air targets of all types... which makes it rather more effective and less collateral damagy.
Your own drones watching your own airspace over your own lines is still the most important thing and its air view of the battlefield can be transmitted to all forces so they know and can defend themselves if needed.