If you had to pick a laptop or mini-PC, which one?

I also have a Intel Nuc.

2 ssd hard drives it runs Plex for just my music right now but also does movies.

Connected to my pre by Hdmi. I was recently told about a linear power supply I can get for it that would further improve sound quality, I am considering it but I think it sounds pretty good right now.

I also have an Oppo I can play music from the Nuc with using DLNA. I have the option of playing from my pre off the Nuc using DLNA as well but being able to use Plex, browse and play music on a 75" tv is tough to beat.

I have no idea what laptops you're looking at but here's one about$400 that would do everything you want. 

https://www.dell.com/en-us/shop/dell-laptops/inspiron-15-3000-laptop/spd/inspiron-15-3593-laptop/nn3...

Do you think an i3 with only 8GB of ram is enough? Also, I have about 100GB of FLACs.  I could connect an external drive but that would take away one of the few USB ports.  Hmmm.

Yikes, a castrated CPU...

With a ssd and 16G of memory? Maybe? I wouldn't personally just not enough horse power for my preference and with the cost of CPUs not really worth it.

I would keep all your music on an internal drive or at least a NAS that connects via ethernet. All my flac are on a internal ssd drive in a Intel Nuc I prefer not to use usb.

To stream music yes it's more than enough. Put your music on one of these. The laptop I linked has a card reader

https://www.amazon.com/SanDisk-256GB-Extreme-UHS-I-SDSDXXY-256G-GN4IN/dp/B07H9VX76D/ref=asc_df_B07H9...