Can I route the neutral wire from a surge protection breaker across the panel busbars?
Having the neutral cross the hot bus is not a code violation.
However since neutrals are not protected for overcurrent, if for some reason a second circuit was tied in and the insulation melted it could damage the panel badly enough to require replacement. I have seen this.
I would route the wire around as not to create this remote but possible hazard.
But your wire is too short? Then splice enough to make it around and this would be a safer method that is also code compliant.
This is the reason electricians that do remodels hate to see wires with no service loops, now the wire requires a splice or less than desirable routing.