First things first. Though mistfire has updated certain aspects of X-Slacko Slim, I don't endorse the use of dated Pups for Internet.
Last post to XOpup / X-Slacko Slim "Is just a plaything?" << But hey, no harm in a test drive.
While either may boot, I feel you'll struggle finding an up-to-date, YouTube compatible browser. Palemoon, if that XO-1 can even open YouTube with a current browser, will be your best bet on the browser side. Low RAM and a not too quick processor are dicey @ best. For these reasons I feel antiX, with its "apt-get" Debian base & low system requirements should be your first choice. You however are in the drivers seat. Try what you like. In fact, try'm all should you not like one or the other.
https://download.tuxfamily.org/antix/do ... index.html
"Base" will give you a few apps; Core will provide even fewer programs but won't bog you down with non-essentials. YOU "sudo apt-get" the browser.
As for how to get the ISO on there, a few choices:
- ISObooter << For test purposes this would be my choice.
- Rufus - Popular.
- Fedora LiveUSB Creator - Or what Fedora recommended back in the day. Seems to have features I haven't seen in other USB installers.