The serial line does not communicate with the touchscreen, so in this aspect you will not be able to do what you seek.
There’s a Cura plugin that will directly load files, so you only have to walk once though. Cura Snapmaker Plugin released. There’s also a Windows Explorer batch script, a python script, some other scripts to do the same manually elsewhere on the forum. The API to upload files is quite simple. File Transfer via WiFi - #5 by zvalentine22
I used PuTTY on Windows and I guess it doesn’t have issues with line endings, not sure there. Maybe the responses could be piped through a regex to do a substitution of LF with CR? From the man page, can you eol CHAR to change the eol char to linefeed?
eol CHAR
CHAR will end the line
* eol2 CHAR
alternate CHAR for ending the line