In low opl if an opponent doesn't come, does 10 minutes rule apply?

Yes — the 10-minute clock applies at every OPL, including low OPL (TR 703.8).

The only OPL difference is the middle tier: arriving within 10 minutes of round start is a Warning + time extension at low OPL (upgraded to Game Loss only at high OPL). Past 10 minutes it's a Match Loss at any level, and if the opponent never shows, they get a Match Loss and are dropped from the tournament unless they report to a judge before the next match begins (TR 703.8.c–d).

Practical advice: you don't get the win automatically at minute 1 — wait at your seat until the 10-minute mark, then call a judge to record the Match Loss in your favor.