sys-ftpd-light VS Rekado

Try https://github.com/cathery/sys-ftpd-light. It's super convenient.

I recommend sys-ftpd lite (which runs in the background), https://github.com/cathery/sys-ftpd-light you need to edit the config.ini located in config/sys-ftpd/config.ini you can configure the user/pass or just enable anonymous:=0 then you can use a client like filezilla, winscp or windows ftp to access your switchs sd card with your switchip:5000 u/ToxiClay you should try this too.

yes you can use FTP, either https://github.com/mtheall/ftpd or https://github.com/cathery/sys-ftpd-light, you still need to transfer your files prior, also you can mount your switch via usbc cable using tegragui, I also believe there's a homebrew app that allows you to access the microsd card via usb cable https://github.com/retronx-team/mtp-server-nx i think

tried to make sys-ftpd-light function, but it still won't.

When using with your phone, you often need a USB OTG adapter. If you're using Android, I'm assuming you're using Rekado. Here's an excerpt from their GitHub page about this:

RCM Loader is not worth of your money, I suggest you to buy an adapter for your phone, installing Rekado and connect your phone with adapter with your Switch. You need something like this, Adattatore USB-C a USB-A 3.0 OTG, USB Femmina a USB-C Maschio Compatibile con MacBook Pro, Samsung Galaxy, Telefoni di Tipo-C, Tablet e Altro (Nero e Bianco) https://amzn.eu/d/eKTem8B). Be sure that it can transfer files and you save 25-30 bucks. For the jig, I bought on Amazon, idk if you can buy it from here. I heard of some people that "handcrafted" their jig with hairpins, idk if works, you should try

Yes, theres an app https://github.com/MenosGrante/Rekado/releases

Some advice for after you've booted into custom firmware and got it all set up: consider using AutoRCM. It corrupts a single byte in the Switch's bootloader which causes it to boot automatically into RCM after every power cycle, eliminating the need for an RCM jig entirely after the first use. All you need to do then is inject your chosen payload using Rekado (if on Android), or iOUSB (if on iOS).

If you have android phone you can use that use the app called rekado that's what I use https://github.com/MenosGrante/Rekado/releases

After looking into how Atmosphere boots by looking for a reboot_payload.bin which you can have as ANY payload file (mine is Hekate) I've not needed to inject it by hand in a long time. And if I do ever need to I do it with my phone even using Rekado

Rekado: Payload launcher and serial number checker for Nintendo Switch