Complex or not

The scenario is A seller has something to sell, a buyer find the advert for this on my platform and pays for it via the platform. Payment goes into the platforms merchant account in which it stays until buyer picks up asset. seller receives his money and fees goes into business account.

On the web development end is it complicated to virtually credit sellers platform account with corresponding amount which will be available for withdrawal once asset is picked up. Essentially the aim would be to somehow visually reassure seller that payment is made.

Thanks for any help :)