Is there a way to introduce a temporary wildcard in Snakemake from a list?

I recently started using Snakemake. I am building a pipeline where the goal is to separate fractions of reads (based on their taxID by classification by Kraken2). I am having problems understanding how I may introduce a new wildcard based on a list of taxIDs.

I have:

1. A list of taxIDs that I want to examine further.
2. A script to extract reads from my original .fastq file based on taxID and the Kraken2 classification

The code displayed below is a subset of the pipeline but captures the problem.
The R-script extract_microbial_taxids.R generates a file with each taxID in a separate line.
The function SplitGenusList() splits this file into an array with each element being a taxID.

I would like to split an input .fastq-file and introduce taxID as a new wildcard – likely based on the taxID list from the R-script. Any clues as to how I may achieve this? The wildcard will then be used for a couple of rules, before only the {sample} wildcard is relevant again.

rule all:
    input:
        expand("data/microbial_taxids/{sample}/genus_list.txt", sample = config["SAMPLE"])

rule extract_microbial_taxids:
    input:
        "data/kraken2_classification/{sample}/{sample}.report",
        config["Rlibpath"]
    output:
        "data/microbial_taxids/{sample}/genus_list.txt"
    script:
        "code/extract_microbial_taxids.R"

    
def SplitGenusList(genus_list):
        genus_list = open(genus_list)
        contents = genus_list.read()
        contents_split = contents.splitlines()
        return contents_split    
    
rule extract_microbial_reads:
        input:
            taxID_list = "data/microbial_taxids/{sample}/genus_list.txt",
            kraken_file = "data/kraken2_classification/{sample}/{sample}.kraken",
            reads = config["reads"]+"{sample}.fastq"
        output:
            taxID_reads = expand("data/microbial_reads/{sample}/{taxID}.fastq", taxID = SplitGenusList(input.taxID_list))
        shell:
            """
            for taxID in genus_list
            do
            python code/extract_kraken_reads.py --kraken {input.kraken_file} -s {input.reads} -o "data/microbial_reads/{sample}/$taxID_.fastq" -t $taxID --include-children
            done
            """

UPDATE

After a lot of help from @Oliver and @dariober, I managed to construct a workflow that does as intended. I learned a few things from this:

1: Rule variables (such as {input.taxID_list}) should be written differently for python, input.taxID_list, and shell {input.taxID_list}.

2: the run command allows to combine python and shell (with the shell()function suggested by @dariober) in a way that seems very handy.

Here is the working code:

rule all:
    input:
        expand("data/microbial_taxids/{sample}/genus_list.txt", sample = config["SAMPLE"]),
     expand("data/microbial_reads/{sample}/extracting_microbial_reads.done", sample = config["SAMPLE"])


rule extract_microbial_taxids:
    input:
        "data/kraken2_classification/{sample}/{sample}.report",
        config["Rlibpath"]
    output:
        "data/microbial_taxids/{sample}/genus_list.txt"
    script:
        "code/extract_microbial_taxids.R"

def SplitGenusList(genus_list):
    genus_list = open(genus_list)
    contents = genus_list.read()
    contents_split = contents.splitlines()
    return contents_split

rule extract_microbial_reads:
    input:
        taxID_list="data/microbial_taxids/{sample}/genus_list.txt",
        kraken_file="data/kraken2_classification/{sample}/{sample}.kraken",
        reads=config["reads"] + "{sample}.fastq",
        report_file="data/kraken2_classification/{sample}/{sample}.report"
    output:
        touch("data/microbial_reads/{sample}/extracting_microbial_reads.done")
    run:
        import os
        genus_list = SplitGenusList(input.taxID_list)
        for taxID in genus_list:
            shell('python code/extract_kraken_reads.py -k {input.kraken_file} -s {input.reads} -o "data/microbial_reads/{wildcards.sample}/' + taxID + '_.fastq" -t ' + taxID + ' -r {input.report_file} --include-children')