With the increasing adoption of orthogonal frequency division multiple access (OFDMA) technology in WiFi networks, achieving ultra-reliable low-latency communications (URLLC) presents new challenges in resource management. We propose implicit channel quality-driven resource allocation (ICQRA), a lightweight framework that avoids explicit channel sounding overhead while maintaining high reliability. ICQRA passively monitors channel quality during normal packet demodulation, proactively detects degradations, and switches to better frequency resources before packet losses occur. Our approach incorporates an adaptive threshold mechanism that learns from transmission outcomes while efficiently coordinating resources across multiple users. Evaluations using both simulations and industrial channel measurements demonstrate that ICQRA achieves near-optimal performance in reducing consecutive packet losses with significantly lower resource consumption compared to existing approaches.