ColorFabb BronzeFill and CopperFill can be as bright as you want them to be, but you have to put in the work. They do not come out of the printer that way. They come out looking kind of like clay and it takes a fair bit of polishing, just like any other metal to get them to shine. When metal is cast or forged or welded it does not come out looking shiny. There is no shortcut, it takes work.

There are no paints that are convincing, the RC hobby crowd has been searching and testing metallics for years and years. Some 'chromes' come sort of close, but not quite.

If you want easy shiny, but not cheap, there are spray coatings available that are almost the same as electroforming. Very convincing metallics but also very expensive. Near perfect detail preservation, but only worthwhile for your very best prints. The whole kit to get started runs around ~$300ish and you'll need to supply your own air compressor and have a well ventilated area.

Other options are electroplating and electroforming, both of which can be done DIY fairly easily, at least with copper and nickel with a bit of Google Fu. You will loose just a tiny bit of detail because you'll need to apply a graphite/acryilc paint mix on the piece before plating so the copper has something to 'stick' to. Not ideal for miniatures with high detail, but for medium size pieces or coins it's a very cool effect and not all that difficult.