Com o GNU sed:
sed -n 's/^ro.product.model=//p;s/^ro.build.version.incremental=//p' file
ou
sed -nr 's/^(ro.product.model|ro.build.version.incremental)=//p' file
Saída:
G900FXXU1BOK6 SM-G900F
ou com a atual bash GNU:
#!/bin/bash
while read -r line; do
[[ $line =~ ^(ro.product.model=) ]] && r="${line#*${BASH_REMATCH[1]}}"$'\n'"$r"
[[ $line =~ ^(ro.build.version.incremental=) ]] && r="${line#*${BASH_REMATCH[1]}}"
done < file
echo "$r"
Saída:
SM-G900F G900FXXU1BOK6