There are standards such as USB, Power Delivery.
Then there are vendor phone specific non standard.
The non standard charging phones will default back to a slower charge speed when they don’t encounter their non standard chargers.
Some phone company worse than others in the ratio between their non standard and standard.
But in the case of portable chargers charging phones it isn’t that critical because there’s is always the standard of 5V 2A 10W. A typical phone has in the region of 10Wh to 15Wh cells, using a 70% efficiency therefore even at 10W you’re only looking at 1.5Hr to 2Hr to recharge the phone. As the phone typically has a battery life well above 1.5Hr-2Hr, means at 10W that’s plenty enough power into the phone to keep it charged or recharge it slowly, not as fast as their proprietary charging technology.
As the portable charger, by definition, is with you constantly, you don’t really lose anything.
So just buy the lowest cost portable charger which is reliable and has capacity to keep you going between times at wall socket.
Don’t trust Ampere, when you look at the screen, the phone ingests power slower. Only a USB meter can be trusted.
As you already bought a portable charger, I’d not buy anything more. If you hadn’t bought I’d be suggesting 10Ah Powercore 10000 PD Slim or 20000 PD essential as two sweetspots right now of value.
I think the Huawei support 18W PD but I know OnePlus doesn’t (10W) the others I don’t know if they support PD above 10W. But as I said, 10W is plenty sufficient in a portable charger.
I’m more concerned with the portable charger input to recharge itself, because if you get that wrong you can find it’s not recharged when you need to go. That is your 2nd question, and yes if you get the two I mentioned above and bought an 18W PD charger they’d recharge in less than 4h and 7h respectively.