Well as per title: if I understand this correctly loot chest loots from the whole map? not just a region like radar or bot networks?

Yes, each loot chest collects loot from a complete surface, which is everything you will see in map view.

oh that's not what I wish, do all those lootchest variants do that?

I haven't tried the other mods myself, so this is just from their description: Loot Chest+ seems to collect loot from all surfaces into one chest for all. Active Provider Looting Chest should be more like what you want. It collects loot in a certain area near the chest, and you can use the circuit network to set the radius and angle of this area.

well, scanning the ground incurs a massive performance penalty. you probably don't want radar-based scanners.

Yeah but it could work like this, but then for each item that is picked up do a check if it is in range of the block picking up the item. Also, I personally rather buy a bigger pc than have such unrealistic loot pickup - I know that there will be a performance issue/scaling issue once I start a mod that has loot anyways. (Unless the mod has other was dealing with loot). Loot is non scalable in anyway and this mod more or less just seems to make loot a "non issue".

If it had a penalty like "energy is consumed based on distance from chest loot is picked up" or similar it would be much more fun/realistic.

well you sound like you know what you're doing! good luck writing your awesome mod or buying a new computer or whatever