There is currently no way to mine a single bitcoin. Instead, cryptocurrency miners will mine one block, with the reward currently set at 6.25 BTC per block. For example, based on the current hash rate, it would take fourteen S19 Pros to mine 1 Bitcoin per month. Or, put another way, one S19 Pro could mine 1 Bitcoin in 14 months (not taking into account the increase in hash rate over time).
If buying 130 AntMiner S9 models is not an option, it takes 22 Bitmain AntMiner S9 models in 360 days to mine 1 Bitcoin.