Using bitcoin-ruby to convert from Cosmos Amino encoded public key values to bech32.

amino_to_bech32.rb

# Prerequisites:
# gem install bitcoin-ruby

require 'bitcoin'

def amino_to_bech32( base64_pubkey_value )
  bytes = [
    *["1624DE6420"].pack('H*').bytes,
    *Base64.decode64( base64_pubkey_value ).bytes
  ]

  Bitcoin::Bech32.encode(
    'cosmosvalpub',
    Bitcoin::Bech32.convert_bits(
      bytes,
      from_bits: 8, to_bits: 5, pad: true
    )
  )
end