Simulating detector and reconstruction effects on physics quantities is crucial for data analysis, but it is coming unsustainably costly for the upcoming HEP experiments. The most radical approach to speed-up detector simulation is Flash Simulation, as proposed by the LHCb collaboration in Lamarr, a software package implementing a novel simulation paradigm relying on Deep Generative Models and Seq2seq attention-driven techniques to deliver simulated samples. Thanks to its modular layout, Lamarr provides analysis-level quantities by applying a pipeline of machine learning-based modules that properly transforms the information resulting from physics generators. Good agreement is observed by comparing key reconstructed quantities obtained with Lamarr against those from the existing detailed Geant4-based simulation. Lamarr has been designated with dual capabilities: it can function as a stand-alone simulation framework, while also being seamlessly integrated into the LHCb simulation software.