If by trained model you mean PGS, yes, it would be trivial. While the fitting of the optimal weights may be computationally intensive, it's still just a simple

If by trained model you mean PGS, yes, it would be trivial. While the fitting of the optimal weights may be computationally intensive, it's still just a simple little linear model: look up the SNP value, add or subtract a small coefficient for each of the 30k or whatever 'activated' SNPs, and get the net total.