Well the Sprut-SD Variant (Tank Killer) based on the BMP-3 Amphib tank carries a 2a75 125-mm smoothbore gun (same as the T-90 Russian tank), the BMD-4 comes with a smaller 100mm gun. Either way - all specs are compliant per RFI and has superior power to weight ratio, because it is way lighter than the ZTD-05 at 18 tons, achieved with an aluminum alloy armor. You can get all sorts of ATGM and missile launcher options which will cost you more coin. Amphib tanks are needed in our army direly because that is our fighting scenario.
Tank Destroyer Sprut-SD with 2A75 tank gun based on BMP-3 chassis (more road wheels/heavier hull for higher 18t weight) - doesn't the turret look like the Coelian of WWII?
Regular
BMD-4 variants (13.6t)
With Kornet E
And here's one that can be a great candidate too except the calibre of the main gun is too small.
2S38 ZAK-57 Derivatsiya-PVO – Self-propelled air defense vehicle based on BMP-3 chassis fitted with a 57 mm autocannon and passive reconnaissance and target tracking equipment.
[71] It is designed to shoot down
unmanned aerial vehicles (UAVs),
cruise missiles, air-to-surface missiles, aircraft, helicopters, and MLRS rockets.
[72] 2S38 is equipped with a TV/thermal-imaging system with automatic target lock-on and tracking capabilities, a laser rangefinder and a laser guidance system. The optical and electronic target acquisition system can spot an aircraft at 6.4 km (4.0 mi) and using sectoral observation can detect aircraft over 12 km (7.5 mi) out. The cannon is fast enough to destroy targets traveling 500 m/s (1,100 mph; 1,800 km/h; Mach 1.5).
Laser-guided,
air burst and specialized anti-drone munitions for ZAK-57 are in development. Its guided projectiles have four wings folded in the casing and controlled by the actuator in the projectile’s nose section, using the energy of the airflow to steer themselves to the target.