Hello
I'm Sagar
I can assist you to install 20.04 LTS on you NUC (Next Unit of Computing) machine as you mentioned you've manged to make bootable flash drive for your machine to install or setup , but still I've not properly understand on which step you are stuck , I'd like to assist you .
I've pretty much experience in linux 'cause I've been using linux when I've enter in IT , I've done various set-up linux distro set-up such as debian , fedora , arch , elemenrty , cent-OS , zorinOS , deepinOS , LinuxMint , not to mention Kali Linux also my native system ... etc , either way I've setup RedHat also . I can help you to make bootable device to till end in which
many concept such as UEFI - Lagacy BIOS and partition schema MBR or GPT as well as LVM for servers...
If you reaced here while reading my proposal you get idea I'm really ... , Please message me , I'll assist or help you to go through it , work with linux is my passion ,
Thank you