The best jigsaws for metal may be the ASTE638 model from Fein, which at this point might be very hard to find since I believe it’s been discontinued in the US. It might still be possible to get one in 110v from the UK.
This Fein saw was specifically made to cut steel from what I can tell.
1,050-2,600 strokes per minute.
No blade orbit function, just up and down with a slightly canted blade holder.
Rated for 10mm mild steel and 6mm stainless.
Simply made but very solid.
Alternatively, Bosch made a jigsaw for metal, Model GST25M. It was never sold in the US, although it was sold in the UK in 110v. It doesn’t seem readily available in 110v even in the UK anymore.
That had a stroke rate of 500-2,600 per minute.
Decent jigsaw will cut metal well even at the higher stroke rate though, unless the metal is some weird alloy like inconel.
Carbide tooth, carbide grit, diamond grit, bimetal, hss, etc. jigsaw blades are all available in Bosch T-shank blades, as are blades for all sorts of plastics and other materials.
As JRW mentioned, a Swag table with a portable bandsaw mounted might also be an option.
Depending on the type of cuts and material/alloy and thickness, a sheetmetal nibbler might also be an option.