The newer ones can provide 60W instead of 30W, that makes it better for charging a MacBook. It should be safe since the device contains protective circuitry. One thing you do have to be ready for is that these devices are rather large so you can't stuff them into a crowded box.
The highest power ones from Apple are the 96W ones for the 16" MacBook Pro. I think the USB-C standard sets a limit well over 100W but only with the proper cables. Not sure how they signal that, because I've bought low-power USB-C to USB-C cables before, and no way were those beefy enough to withstand 100W.
Strike that. Apple has a 140W one now.
140W USB-C Power Adapter
The 140W USB-C Power Adapter offers fast, efficient charging at home, in the office, or on the go for your 16-inch MacBook Pro (M1, 2021). Buy now.
www.apple.com