Little Endian Number to String Conversion

05AB1E, 10 9 bytes

žJ+h¦2ôRJ

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-1 byte by inspiration of the Jelly answer.

žJ+   add 2^32 to input
h     convert to hex
¦     drop leading 1
2ô    split in groups of 2
R     reverse groups
J     and join them

R, 54 53 bytes

format.hexmode(scan()%/%256^(0:3)%%256%*%256^(3:0),8)

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Each group of 2 characters is actually the hex representation of a digit in base 256. scan()%/%256^(0:3)%%256 converts to a base 256 number with 4 digits reversed, ...%*%256^(3:0) joins them as a single integer, and format.hexmode(...,8) converts that number to its hex representation with 8 digits.

Python 3, 37 bytes

lambda n:n.to_bytes(4,"little").hex()

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Arithmetic-based recursive solution (50 49 bytes, works also for Python 2):

f=lambda n,i=4:i*'1'and"%02x"%(n%256)+f(n>>8,i-1)

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-1 byte thanks to @JonathanAllan