Have we developed the tech to go from mammal -> digital genome sequence -> physical replicated chromosome -> egg implanted with chromosome -> developmentally normal mammal -> fertile offspring, yet, or is that somewhere in the future?
No. That chain ends at the second step "digital genome sequence". In principle, we could synthesize a bunch of DNA strands corresponding to the genomic sequences and ligate them all together (although it would be absurdly expensive and laborious), but this would not constitute a chromosome. Eukaryotic chromosomes are organized in the nucleus by a huge variety of scaffolding and modifying factors (histones, etc.) into structures called chromatin. Recapturing this from sequence data is impossible, even in principle; the information is just not there. Indeed, understanding nuclear organization at a bunch of different leves is one of the big challenges of modern genetic research.
Have we developed the tech to go from mammal -> digital genome sequence -> physical replicated chromosome -> egg implanted with chromosome -> developmentally normal mammal -> fertile offspring, yet, or is that somewhere in the future?