Over the last decade, near real-time analysis of GPS data has become a well-established atmospheric observing tool, primarily coordinated by the EIG EUMETNET GPS Water Vapour Programme (E-GVAP) in Europe. In the near future, four operational GNSS will be available for commercial and scientific applications with atmospheric science benefiting from new signals from up to 60 satellites observed at any one place and time, however, many challenges remain regarding their optimal combined utilization. Besides raw data streaming, recent availability of precise real-time orbit and clock corrections enable wide utilization of autonomous Precise Point Positioning (PPP), which is particularly efficient for high-rate, real-time and multi-GNSS analyses. New GNSS constellation signals, products and processing methods suggest the development of advanced GNSS tropospheric products, in support of weather numerical prediction and nowcasting will be substantially improved. Such examples are: ultra-fast and high-resolution tropospheric products available in real-time or on a sub-hourly basis, parameters monitoring tropospheric anisotropy above the station (such as horizontal gradients and tropospheric slant path delays), and indicators of severe weather such as extreme convection. Development of advanced GNSS tropospheric products within COST Action ES1206 benefited from two dedicated campaigns prepared for a collaborative effort: (1) the benchmark campaign and (2) the real-time demonstration campaign. The former served for estimating and assessing horizontal tropospheric gradients and tropospheric slant delays, estimated from GNSS, Water Vapour Radiometers and Numerical Weather Model (NWM) ray-tracing. The second campaign developed new software and strategies for real-time, multi-GNSS, high-rate tropospheric solutions including the assessment of pre-operational solutions. The impact of selected processing strategies and precise models were assessed during a long-term GNSS reprocessing campaign aimed at providing homogeneous tropospheric products for climate research. Using information from modern NWM forecasting systems, a variety of tropospheric correction models for real-time kinematic GNSS positioning were developed and assessed. Finally, a transfer of knowledge such as support for establishing new GNSS Analysis Centres and inclusion of new networks into E-GVAP were completed.