can't see the note being replied to but wasm and some fairly uncommon devices are still 32 bit, but most devices now have 64 bits. C++ has a uint128 type that is used in bitcoin core's libsecp256k1, but it's just assembler implementation of the overflow from the LSW to the second for 64bit x 64bit numbers, and it's actually used 4x64bit for scalars and 5x52bit for affine... something or others. the btcec used in most go apps for this curve uses 32 bit integers with the same carry algorithm, and 8x32bit and 10x26bit if your cpu has 64 bit unsigned integers, it's almost twice as fast as using 32 bit integers with 64 bit outputs for the carry algorithm.