Could also just do a flitch plate above the door, doesn't look too hard
Mild Steel Flat Bar | 120mm x 10mm | Steel Flat Bars
Mild steel flat bars (120mm x 10mm), used for joining to other plates to add resilience and stability. Buy steel from local suppliers.
shop.buyabeam.com
How to make a flitch beam for a garden room with a large span roof
We did this before, but probably never did a decent video.hope this explains it more.
youtu.be