Nothing wrong with Android Go.
It is a small, efficient, unbloated version of the normal Android OS.
How do I know?
Because I am using one right now to type this.
But, like any other device running any OS, the stock apps generally suck.
And any stock app from Google is going to suck even worse.
(Google Go, Files Go, etc.)
So, that being out of the way, let me give some 'simple' advice.
https://www.simplemobiletools.com/
Find the apps you want to try.
I suggest Gallery Pro and File Manager Pro first, to solve your immediate problem with moving files.
Do not mess with Google Play Store, as the Pro versions of the apps are available on F-Droid.
F-Droid is excellent, the other members here will verify that.
https://f-droid.org/
Iam using the same OS as you, and I replaced all of the stock apps that I could with Simple Mobile Tools.
There is nothing wrong with a cheap device, you just need to make it work for you.
The funny thing is- even if I had a high dollar device, these are the same apps that I would want to be using.