The links are broken. These should work:
- https://www.aliexpress.com/item/1005...martRedirect=y
- https://www.aliexpress.com/item/1005...martRedirect=y
- https://www.aliexpress.com/item/3304...martRedirect=y
- https://www.aliexpress.com/item/1005...martRedirect=y
I have no experience with Brompton bags. It is nice to have front bags that don't affect the steering, like a handlebar bag or front panniers do. Though some people may find the Birdy twitchy, and may like some steering weight to stabilise it.
That front latch opening seems rather dangerous, best to be sure you're protected against that. One might also argue it could be a risk to load the Birdy frame in a way it isn't built for. The Brompton frame is built for this front load.
There are rear racktop bags that are as easy to pop on and off as a front bag. Since you have the rear rack already, and it is useful anyway for rolling the folded bike, I would go for that first and then consider front cargo later if there is a need.