Sony Reportedly Building Lighter 400mm & 600mm Primes

Sony bird and wildlife shooters have long complained that serious reach means serious weight — a lightweight 400mm or 600mm prime would change that calculus entirely, especially against Canon's RF 600mm f/11 and Nikon's Z 600mm PF. But this is thin rumour territory with zero specs or dates attached, so file it under 'interesting if true' and keep shooting with what you've got.