First of all, I want to say I really like both of these songs!

regardless of what was used in the original recording, I think you could approximate both of them pretty well with an electric guitar and finger slide. A volume pedal would be really useful to obtain the fade-in, but you can also do that by rolling on the guitar's volume knob with your little finger

In order to get enough string height on an electric guitar (which would typically be set low) I slide a small nail between the strings and fretboard. This is something that can be done quickly for one song, then removed just as quickly for the next song. Experiment and use the smallest nail possible to achieve resonance with the slide. The larger the nail, the harder it will be to insert it.

As far as where to put the nail, that depends on the key of the song. I like to put it on whichever fret would be the key if a 1st position style A chord were played there. That way open strings on the B G and D should fit most places in the song

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0