If one wanted to avoid buying the BMW fasteners then button head stainless fasteners with appropriate sized spacers could be used instead. Most of the body work are m5 x 0.8 fasteners. Personally I would avoid slotted pan head (e.g., use a "minus" screw driver). And I would prefer not to use phillips pan head (e.g. use a "plus" screw driver). I would prefer using either button socket cap (that use the allen key) or torx button cap screws. These fasteners usually lack the pointed end and do not have a flange head. A half-inch outside diameter (#10 or 1/4 inch ID) washer could serve instead of a flange head.
Some spacers that could be used are shown in the links below -
https://www.amazon.com/gp/product/B074P2CZ33/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FGA6198/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FGA28Q8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FG9Y3IU/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
Some spacers that could be used are shown in the links below -
https://www.amazon.com/gp/product/B074P2CZ33/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FGA6198/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FGA28Q8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FG9Y3IU/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1