Do you want only the mtDNA (no nuclear DNA) or is it OK to get the nDNA as well? Any standard DNA extraction kit will give you both nDNA and mtDNA (e.g. Qiagen DNeasy kit).

Thank you for your reply! :) I would be interested in knowing if there is a commercial kit suited only for mtDNA extraction (without nDNA)?

There are kits that would at least enrich the mitochondrial DNA.

I think something like this would work for you https://www.thermofisher.com/order/catalog/product/89874#/89874

https://www.qiagen.com/se/products/discovery-and-translational-research/dna-rna-purification/dna-purification/plasmid-dna/qiagen-plasmid-kits/?clear=true#orderinginformation