Yasir, I think I’ve shown on my VIM3 Twister OS forum topic, that it’s not very hard to get a working Armbian image with full hardware support running from the micro-SD or USB. The base for this is a working Rockchip64 image with a DTB swap, then after a fully-functional boot, apt install of replacement kernel packages. Almost, if not quite, trivial. 
Any concern about my beginning with a Twister OS image.xz should be allayed, knowing that this is straight Armbian+Focal, with a bunch of desktop-focused, post-install packaging and configuration.
This should be no different for a VIM3L, as far as I can tell.
Two tasks remain: Audio device support and eMMC flash.
1 - Audio device hardware is all present and accounted for in loaded kernel modules and ALSA detection. This means we probably have a tangled Pulseaudio problem. Don’t get me started! Anyways, I see light at the end of this tunnel!
2 - I will ignore Hyphop and Balbes flamewars. If I can get an image.xz written to SD, then use regular tools to transfer this to eMMC, I will do it, and I will also generate a “community release” of the Twister OS image for others. Given a little time, I’d duplicate the packaging effort for a clean, vanilla Armbian “community release”.
In fact, I’d do this today, but won’t start until audio works over HDMI. If people are going to be nasty about versions of boot loaders, then at least I will make sure a release needs no other apologies.