Inquiry about Physical SIM Cards with International Roaming Data Packages

We are looking for a reliable long-term supplier for physical SIM cards with flexible international data packages. Our business is located at a major border crossing area in Türkiye, serving international travelers and truck drivers. We need coverage for Türkiye, Europe (Bulgaria, Romania, Greece, Hungary, Austria, Germany, Italy, France, Spain, Belgium, Netherlands, etc.), Balkans (Serbia, North Macedonia, Bosnia & Herzegovina, Montenegro, Albania, etc.), Caucasus (Georgia, Azerbaijan), and potentially Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan, and Russia. We prefer reusable/rechargeable SIM cards managed through a B2B portal, recharge platform, or API. We need the ability to customize packages by country groups and data volumes. Please provide details on wholesale pricing, MOQ, payment terms, and whether sample SIM cards can be provided for testing before larger orders. We are interested in a long-term partnership with high-volume potential.