They should have made IBIT be 1/100 or 1/1000 of the BTC price.
For SPY they make it be roughly 1/10 of the S&P price.
Discussion
You can't because you have management fees reducing the BTC / share every year. Rather just make it a random number.
0.12% per year would mean 1% diff every 8 years.
SPY has been able to keep it's price within a few % of 1/10 of SPX for +20 years and they even have the handling of dividends to manage for the difference.
Every 10 years you can do a small stock split to rebalance if needed.