I think some of the ‘leaks’ may be the result of temperature fluctuations, with the air in the can expanding and forcing oil up the pick-up tube. The resevoir should have a small ‘breather’ hole.
Being reluctant to spend money, and liking simplicity, for years I’ve used cheap plastic dispenser bottles, whose nozzles aren’t connected to a pick-up tube in the oil – they have to be pointed nozzle-down. They have a ‘bellows-like’ lower body, so are convenient and easy to squeeze. Provided they are stored upright, only the residue of the drip-on-the-end-of-the-nose is a potential mess-maker, and it ‘sniffs’ when you let go, so not a real problem. These are fine for dropping oil where it’s needed, but, for pressure oiling, not much use. So cheap, you can have them scattered all over the place…