You could probably double two wires to get higher current capability, so you could use thinner wires for signals.
For example the classic ribbon cable, 14 pin with polarizing key, 45cm long :
https://www.digikey.com/en/products/detail/assmann-wsw-components/H3CCS-1406G/121858160 cents if you get 100 ... maybe cheaper if you go around digikey
You can cut it in two at 20-22 cm length, and you have two cables for 30 cents each.
ex 40 cents if you get 200 , 14pin 30cm cable :
https://www.tme.eu/en/details/ds1052-142b2na2030/ribbon-cables-with-idc-connectors/connfly/ds1052-142b2na203001/(and if you don't need 30cm in your product, you can cut the cable in the middle and get 2 x 15 cm cables for the price of 1.
10 pin or 20 pin headers and ribbon cables should also very cheap as they're used for USB 2.0 and USB 3.0 on motherboards.
You could maybe work around the latch by having a T or L shaped piece of wire or something soldered near the header, so that you'd have to bend that to plug the connector? Or maybe if the case is low height, maybe just have some thermal pad or something between the box and the connector to put pressure on the connector and keep it in?
Friction should be sufficient to keep the cable in the connector
or make your own
ex 60k pieces in stock 10 pin (2x5) for <20 cents in volume :
https://www.digikey.com/en/products/detail/on-shore-technology-inc/101-106/2794212Ah just read the last which says spade terminals. Are there no spade terminals compatible with awg28 ?