Uy bro, nice goal! For compact programmable router, maganda na yung mga GL.iNet devices like yung GL-AR150 o GL-MT300N-V2. OpenWrt-based na siya out of the box kaya highly customizable - pwede mo i-setup yung captive portal for business, VPN, bandwidth control, etc. Sulit na sulit tapos maliit lang talaga siya.
Pwede rin yung Raspberry Pi + extra network adapter then install OpenWrt or pfSense, mas flexible pero medyo more setup involved. Kung gusto mo talaga ng "ready na programmable router", go with GL.iNet - bet na bet ko yan for small projects. Check mo sa Shopee meron usually mga sellers nun. Good luck sa business pre!