The code in the post doesn't seem to finish the job. For a timestamp like "2023-07-02T15:46:00Z" or the other formats you mentioned, the timestamp fits in a sin

The code in the post doesn't seem to finish the job. For a timestamp like "2023-07-02T15:46:00Z" or the other formats you mentioned, the timestamp fits in a single 32-byte register, so you could write code that deals with the stuff as it is. If you have a mix of timestamps with different numbers of decimals or with different time zones, dealing with those things will take a bit of work compered to the ideal case where you had all "Z" or all "+" or all "-" for the time zones and all the same number of decimals for the fractional seconds.