Dynamic operating envelopes (DOEs) are promising to cater for the strong uptake of distributed energy resources (DERs) in low-voltage (LV) distribution networks while ensuring secure network operation. Under the current framework, DOEs only specify active-reactive power set-points at households' point of connection (POC). In this regard, DOEs do not provide information on the feasible operating region (FOR) of end-users, which is helpful for an aggregator's market decisions. This article proposes a near real-time approach to determine DOEs that specify the FOR at end-users' POC in an LV distribution network. First, Latin hypercube sampling (LHS)-based load flow studies are performed to identify feasible pairs of P-Q injections at the POC that would not breach voltage limits. Secondly, the convex hull of feasible pairs is constructed to obtain household DOEs. Finally, a feeder-level time-varying envelope that represents the aggregate flexibility of downstream nodes of the network is calculated. A comprehensive analysis on a real Australian LV distribution network using realistic data suggests that the proposed approach is scalable and encourages active power exports beyond current industry practice. Moreover, the framework ensures privacy and separation between the distribution network service provider (DNSP) and the aggregator aligned with the existing policy and regulatory frameworks.