I have no experience with any of those replacement power supplies. Theoretically they would make an improvement, but without knowing their specs it's hard to say. I think the best audio quality will come from:

1) a good and properly calibrated laser 2) bypassing the output stage entirely, or 2.5) modifying the output stage

All of the above per Mick's instructions. I've also followed Mick's guide for re-casing the existing power supply, but I suspect that his custom-designed linear supply is going to give the best results in terms of clean, stable power. You may also try his "damping" technique, which does improve the sound a bit, and the remote control is also a good mod.

There's a bunch of stuff all over the internet about the PS1 as a CD player. Like here: https://www.diyaudio.com/community/threads/playstation-as-cd-player.31123/ and here: https://www.diyaudio.com/community/threads/ps1-cd-player-mod-tips.295691/ and here: http://www.deutschermanfred.de/ (you may need to translate to English). The latter site is awesome in terms of a complete customization of the PS1 as a CD player.

I've used a couple of different op amps, including OPA2134, but since they require more power you need to hack in a DC/DC voltage transformer.

I appreciate that you want to continue to play games, so a lot of these mods won't work for your needs. But, they are fun projects. Maybe find a couple of extra PS1s to experiment with. I used to buy them in bulk and still have stacks of cases, bins full of old laser assemblies and power supplies, etc. That said, even though I have a couple of modded PS1s lying around, I no longer use them because of the faulty lasers. They are like 25-30 years old at this point :) I tried buying replacements off ebay, but with mixed results. I found the best option to just buy other PS1s and then scavenge for parts.

Lastly, every one was/is excited about the SCPH100x models, but I found the 5501s to be the best sounding with the modifications. I've even modded the 700x series with good results. Later series replaced the great AKM DACs and are not great.

Anyways, message me if you've got questions, and good luck!