Can I run a single Magento for Poland + Czech Republic + Slovakia + Hungary (CEE)?

Yes, Magento’s multi-store architecture handles PL + CZ + SK + HU cleanly. CEE cross-border is a natural expansion path for Polish brands (shared logistics, similar consumer behaviour, EUR-or-local-currency split):

• Single Magento backend, 4 stores, one each for PL (PLN, Polish), CZ (CZK, Czech), SK (EUR, Slovak), HU (HUF, Hungarian). Shared catalogue, separate URLs (yourbrand.pl / .cz / .sk / .hu) or one domain with country selector.
• Per-store currency, PLN, CZK, EUR (SK), HUF. Auto-FX rates daily via ECB / NBP. Magento currency_rate table per store.
• Per-store VAT, PL 23%, CZ 21%, SK 23%, HU 27% (highest in EU). Each with reduced rates. Magento tax_zone rules per store.
• Per-store payment methods, PL adds BLIK + P24 + PayU, CZ adds GoPay + ComGate, SK adds Tatra Pay + 24-Pay, HU adds Barion + OTPay.
• Per-store shipping, InPost Paczkomaty for PL (huge in PL/CZ/SK now too), DPD CZ for CZ, Slovenská Pošta for SK, MPL / GLS for HU.
• Per-store legal pages, RODO/UODO (PL), GDPR/ÚOOÚ (CZ), GDPR/ÚOOU SR (SK), GDPR/NAIH (HU).
• Per-store language, Polish, Czech, Slovak (often substitutable with Czech for tier-2 stores), Hungarian. Translations via Magento i18n CSV.

Architecture decided in the audit step, depends on whether you want one domain or four.