First post and happy to be here!
I’m seriously considering buying an OP-1 in the next couple weeks, but I’m looking for some information and advice.
Can the OP-1 do a typical “hollow” sounding pulse wave, like the one on the PO-128?
Does anyone like using their OP-1 for making chiptunes?
Edited this for you… “I’m buying an OP-1 in the next couple weeks”
It can pretty much do anything so I think universally you’re going to get “just buy it”
There’s a great resource at https://op1.fun that you can use to load in patches and samples so if you can hear it, you can play it. Not sure which one from the Megaman PO you mean but there’s a patch on there already which might be what you’re looking for:
https://op1.fun/users/endmii/patches/po-128
For chiptunes it’s perfect. I have the PO-20 Arcade which does a wonderful job of that as you’d expect and you can get the main samples from that here op1.fun - PO-20Arcade by enotide
Or get both 
You can’t go wrong.
I find the OP-Z a great half way between the two for 8-bit era music so you could look into that as well. The OPFun samples work on that as well. Sorry if I’ve just put you on bread and water for a month but it’ll be worth it.
Now, if you still need convincing take a look what @cuckoo put together 9 years back. At the 11 minute mark your credit card should be close by CUCKOO - OP1 NES 8-bit presets and tunes - YouTube
The synth engine called Dr Wave is great for creating old NES type of sound waves like that. And where the synth engines are not what you’re after, the sample engine can probably get you there.
CUCKOOooo !!! 
Ha ha ha, thank you for editing my post!
itsnotnoise, and cuckoo, you two have really helped me decide. I just went to OPFun and already found lots of great sounds. Thanks for the links! Those sample chains are perfect for what I want to do.
Just watched cuckoo’s video and the sound at 8:15 is exactly what I wanted to hear. I appreciate all the help.
I am really pleased to know that Dr Wave will get those sounds, and for what I can’t generate through synthesis, I can just use a sample.
I probably should revise my post from “a couple weeks” to " a couple days"!!!
This is awesome !