The short answer is that a traditional appeal is almost certainly not available at this point, but there are other avenues worth understanding.
Direct appeals in the federal system, which is where bank robbery cases almost always land since robbing a federally insured bank is a federal crime, have strict filing deadlines. A direct appeal has to be filed within 14 days of sentencing. A motion to vacate, set aside, or correct the sentence under 28 USC Section 2255 has a one-year statute of limitations from the date the conviction becomes final. Ten years out, both of those windows are closed in almost every circumstance.
What remains available after that window depends on what the argument would be. If new evidence has emerged that was not available at trial, if there has been a change in the law that applies retroactively to the sentence, or if there are constitutional issues that were not previously raised, there are narrow pathways that courts will sometimes consider even years after conviction. These are difficult to win but they are not impossible, and an attorney who specializes in federal post-conviction relief is the right person to evaluate whether any of those arguments exist.
Ten years of clean institutional behavior is genuinely valuable, but it does not by itself create a right to appeal or a mechanism to reduce a sentence. What it does do is build the strongest possible record for any parole or early release consideration that exists within the sentence structure, and for compassionate release consideration if health or other circumstances warrant it.
The First Step Act is also worth exploring. If the sentence involved any drug-related enhancements or mandatory minimums, there may be retroactive relief available depending on the specific charges and sentencing guidelines that applied.
An attorney with federal post-conviction experience is the essential first step before pursuing any of these options.