I think you could possibly be mistaken here pal. A halogen GU10 fitting will power up an LED GU10 no probs. The clue is on the fitting GU10. Unless of course you don't have GU10s. More probably 12v halogens which are not mains GU10s.
You're talking about something else, not GU10 bulbs
That usually be mr16, not gu10
Transformers for 12v downlighters typically don't support the low current draw that LED bulbs use and will usually either not work at all, flicker or flash, and may also not support dimming at all.
LED is the only sensible choice in 2019! I have taken working halogens to be recycled. I also like that LEDs can be any shade of white you want even though most shops still sell them at 2700K (i.e. warm white).,