Consider Epoxy grouting which doesn’t need a sealer and its more wear resistant against scratches/liquid spills.
If using flat tiles can also opt for ‘marble gum’ which fills the gap to create a seamless no tile gap lines.

Traditional grout sealer can use following. Available to ship to SG via Amazon.
FILA Surface Care Solutions MP90 ECO PLUS High Performance Penetrating Stone Sealer

FERUNI CERAMICHE SDN BHD NO.12 JALAN 51A/213
SEKSYEN 51A
SELANGOR - Malaysia

janechin@feruni.com


Listed from FILA’s website
https://www.filasolutions.com/usa/products/...ral-effect/mp90