1st option:
Browse: https://valheim-map.world/
enter your seed
tick checkbox "Show Trader"
note position (rougly)
play your map and find the trader


2nd option:
actiavte cheats


3rd option:
bring the stuff from another world where the traders location is known


4th option:
keep searching

3rd option is valid imho as one allready moved around to find the trader
just play valheim you see fit with your own set of rules (not cheating or doing all the stuff the old fashioned way) its up to you