Are there any potential issues with putting a 90° bend straight from a shower drain into a 50mm waste pipe? It then falls 10mm over a 1m span into a waste manifold.
Connecting an elbow directly to the shower strainer is not a problem, 2" hopefully. Use as long of radius bend as you can. Keep a good slop in the drain line. Shower drains only handle water and not very much at a time. They rarely clog.