After ~15 years of literally the world's smartest people trying to come up with exactly that (some of which are dear friends), the only way conscionable way I can regard QC is as a vapor bubble.
In 2000, it was a fantastic looking technology that looked like it was going to leapfrog classical computing in a whole lot of ways. Now, classical computing has gotten so fast that (for example) O(sqrt(n)) searching of an in-memory structure is just not that exciting - O(n) is totally fine with a 100 GB dataset for many cases, and loading your database into your quantum computer would be O(n) anyway. Ideas for quantum machine learning have been supplanted by LLMs, and Ising optimization machines have already failed in the free market compared to a lot of classical computers.
The remaining problems of interest are quantum simulation and encryption cracking, both of which are relatively niche markets.
Where changes would be needed is in digital signatures and certificates and in the key exchange algorithms for the establishment of communication connections in the public Internet, where pre-shared secret keys are not used.
Many algorithms have been studied, but they are significantly less efficient than those used today.
Actually, several post-quantum algorithms are considerably faster than current algorithms. But they have much larger ciphertexts, signatures, and public keys.