Yes, since the original bud wood is from the polyembryonic Lemon Zest, the resulting seedling should be polyembryonic with the caveat that polyembryonic seeds sometimes has a single seedling coming up.
Sequencing is getting cheaper every year and there are small sequencing machines that are very small and portable such as Illuminas products. Sequencing is the easy and cheaper part of the equation. It's the DNA extraction that is more laborious and expensive. For DNA extraction and sequencing, efficiency of scale is the name of the game.
To sequence one sample can cost several hundred dollars but if you run thousands of samples, the cost can be as low as $10 a sample or less.
Simon