For anyone else looking, u/Heratiki 's help led mt to these items on Amazon.

M3x5mm with countersunk head

https://www.amazon.com/uxcell-M4x10mm-Machine-Stainless-Fasteners/dp/B07WMFWP87/ref=sr_1_2?content-id=amzn1.sym.918a99dd-4826-4c0a-be33-a6705d69c4cf%3Aamzn1.sym.918a99dd-4826-4c0a-be33-a6705d69c4cf&crid=2SC4JO0SX91UR&keywords=Screws&pd_rd_r=90a47932-bc29-4815-a008-cabba2d184b1&pd_rd_w=eBh1G&pd_rd_wg=Hi7tt&pf_rd_p=918a99dd-4826-4c0a-be33-a6705d69c4cf&pf_rd_r=DCN6GJ7ZPAQ6HJNKH4B1&pid=7mLbOd6&qid=1655415905&refinements=p_n_feature_five_browse-bin%3A3177279011%2Cp_n_feature_two_browse-bin%3A2292860011%2Cp_n_feature_twenty-eight_browse-bin%3A19043863011%2Cp_n_feature_fourteen_browse-bin%3A11434056011&s=industrial&sprefix=m4x10%2Bwith%2Bcountersunk%2Bhead%2Caps%2C88&sr=1-2&th=1

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M4x10mm with countersunk head

https://www.amazon.com/uxcell-M4x10mm-Machine-Stainless-Fasteners/dp/B07WCT77LR/ref=sr_1_2?content-id=amzn1.sym.918a99dd-4826-4c0a-be33-a6705d69c4cf%3Aamzn1.sym.918a99dd-4826-4c0a-be33-a6705d69c4cf&crid=2SC4JO0SX91UR&keywords=Screws&pd_rd_r=90a47932-bc29-4815-a008-cabba2d184b1&pd_rd_w=eBh1G&pd_rd_wg=Hi7tt&pf_rd_p=918a99dd-4826-4c0a-be33-a6705d69c4cf&pf_rd_r=DCN6GJ7ZPAQ6HJNKH4B1&pid=7mLbOd6&qid=1655415905&refinements=p_n_feature_five_browse-bin%3A3177279011%2Cp_n_feature_two_browse-bin%3A2292860011%2Cp_n_feature_twenty-eight_browse-bin%3A19043863011%2Cp_n_feature_fourteen_browse-bin%3A11434056011&s=industrial&sprefix=m4x10+with+countersunk+head%2Caps%2C88&sr=1-2

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Amazon Calls these "Flat Head Machine Screws Inner Hex Screws"The filter system under a search for "screws" was really helpful actually.  

https://www.amazon.com/s?k=Screws&rh=n%3A16310091%2Cn%3A17290023011%2Cn%3A383599011%2Cp_n_feature_five_browse-bin%3A3177279011%2Cp_n_feature_two_browse-bin%3A2292860011%2Cp_n_feature_twenty-eight_browse-bin%3A19043863011%2Cp_n_feature_fourteen_browse-bin%3A11434056011&content-id=amzn1.sym.918a99dd-4826-4c0a-be33-a6705d69c4cf%3Aamzn1.sym.918a99dd-4826-4c0a-be33-a6705d69c4cf&crid=2SC4JO0SX91UR&pd_rd_r=90a47932-bc29-4815-a008-cabba2d184b1&pd_rd_w=eBh1G&pd_rd_wg=Hi7tt&pf_rd_p=918a99dd-4826-4c0a-be33-a6705d69c4cf&pf_rd_r=DCN6GJ7ZPAQ6HJNKH4B1&pid=7mLbOd6&sprefix=m4x10+with+countersunk+head%2Caps%2C88&ref=sr_es_fst_scr

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M4x10mm with cylindrical head

https://www.amazon.com/Fullerkreg-Socket-Stainless-Machine-Quantity/dp/B07CJ7PSS9/ref=sr_1_9?crid=2DFD9JVFQ3RVQ&keywords=M4x10+with+cylindrical+head&qid=1655415613&sprefix=m4x10+with+cylindrical+head%2Caps%2C109&sr=8-9