PSP Go is great. The only issue is battery life (3-4 hours). Not sure if you can get more out of it with just music. Carrying a portable battery bank solves that problem though.
The speakers themselves are weak - worse than most phones. If you want a great stocking stuffer, this little headphone amp/speaker sounds awesome and works well with the PSP Go. Otherwise, you should be able to use headphones or anything bluetooth.
Ok so I suppose the two power banks would work best. Is raspian the same as retropie? I believe I just updated to 4.2.2(?) yesterday. Would that be the same?
Edit to add: what about a speaker? Would this work?
https://www.amazon.com/dp/B01NAFNT1M/ref=cm_sw_r_cp_api_oCT-ybDBMPX9G
(Sorry not sure how to make clickable link and I'm on mobile.)
I have the gold and it looks amazing, but it looks weird next to the Switch's blue and red.
If you want another fun little gadget for the switch, this speaker fits in the headphone jack and makes the handheld sound a good bit better. I love it. Works great on other handhelds too (3ds, 2ds, PSP).
There's no way to do that without modding it. But you could buy one of those small speakers that connect to the headphone jack - they don't add to much bulk to the iPod: https://www.amazon.com/Portable-Speaker-Lithium-Interface-Computer/dp/B01NAFNT1M/ref=sr_1_7?dchild=1&keywords=mini+speaker+headphone+jack&qid=1601663121&sr=8-7
I bought [this one from Amazon](https://www.amazon.com/Portable-Speaker-Lithium-Interface-Computer/dp/B01NAFNT1M/ref=sr_1_5?dchild=1&keywords=small+speaker+headphone+jack&qid=1596375560&sr=8-5 ).
It works great on my 2ds XL and some of my other handhelds. Much louder and a bit more bass than you'd expect.