Do you need both a pixel and a conversions API?
Run both transports with a shared event ID — redundancy plus deduplication is the recommended setup.
Yes — run both. The browser pixel and the server-side conversions API carry the same events over different transports: the pixel is easy to block, the API is durable but blind to some on-page context. Send each event through both with a shared event ID and let the platform deduplicate; you keep coverage without double-counting.