Is it possible to get the raw data (fastq) from some dataset?

All the raw fastq files can be downloaded from GEO (e.g. https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE109125).

Please check the 'SRA Run Selector' at the end of the webpage. You can also use NCBI SRA Toolkit to fetch the data directly from NCBI. Here's the documentation: https://github.com/ncbi/sra-tools/wiki