Don't right now. You won't get HDR on the pi4 for a while so you won't get any immediate benefit.
I've been running an s905x mecool android box purely booting from micro SD card and it's been superb. Rock solid, HDR, zero crashes. Cost £25 on eBay.
I've got all the Pi's and used '#elec' for all of them. The alpha2 isn't quite ready IMHO, the kernal change is needed etc. This is not a dig or criticism of the libreelec team, quite the opposite. They do amazing work, just need to understand nothing can be ready and be perfect immediately when new hardware is released.