This is a DSHK .50" (roughly) caliber heavy machine gun, converted to an infantry support weapon. Typically these guns are mounted to a tripod or vehicle, but Ukraine has been converting these to infantry support weapons by adding a bipod, carry handle, shoulder stock, gigantic muzzle break(to make recoil bearable), new handle and new trigger assembly.
For anyone wondering, a DSHK heavy machine gun is 34kg or 75 pounds.
Here's a video that discusses it in detail, and covers similar american prototype conversions with their equivalent heavy machine, the M2 Browning (38kg, 84lbs). https://youtu.be/fd98XcRm0bM?si=MebMTYuxTRKu2cHV
Ukraine has been converting these to infantry support weapons by adding a bipod, carry handle, shoulder stock, gigantic muzzle break(to make recoil bearable), new handle and new trigger assembly.
That laundry list of upgrades makes me appreciate how hard it must be to machine a good receiver and barrel for something like this; those are practically the only parts not listed.
It takes a huge amount of industry to produce firearms, not just the precision in machining, precision of alloys used, heat treatment of steels, supply lines, etc. Missing one of these vital attributes will lead to, at best, an unreliable weapon, or at worst, something that will explode and potentially kill the user.
As Ukraine is the poorest country in Europe fighting the largest European war since WW2, anything that can shoot accurately is precious, especially a big ass .50 with a very long range. As they say, its hard to hide from a .50