I ordered one of these. Looks ideal.
https://www.redballoonind.com/product-page/fanny-packin-fanny-pack-holster
Low-profile gun bag to lug around with me while I'm out with the wife and kids, by Fieldcraft Survival.
#EDC #LaserRecommended
https://fieldcraftsurvival.com/edc-belt-bag
https://nostrcheck.me/media/public/nostrcheck.me_1116327425833835051692635254.webp https://nostrcheck.me/media/public/nostrcheck.me_4562154263121479621692635264.webp
Discussion
That should do the trick. You have something to keep it attached to the bag so you can draw and the kydex falls away as you do?
The entire back of this holster is velcro, and the dedicated pocket in the gun bag is hard velcro. Match made in heaven.