Growing demand for sustainable fuels and chemical feedstocks has intensified interest in waste- and biomass-derived oils as circular carbon resources. This study presents a techno-economic and GHG assessment of methanol production from three unconventional liquid feedstocks: waste lubricating oil (WLO), tire pyrolysis oil (TPO) and fast pyrolysis biomass oil (FPBO). Each feedstock is converted to synthesis gas via oxygen-blown entrained-flow gasification and subsequently processed through catalytic methanol synthesis. Process simulations were developed in Aspen Plus® and evaluated across plant capacities of 20–100 MW, under both conventional and hydrogen-assisted configurations. Carbon conversion to methanol increases substantially with hydrogen integration, rising from ∼22 to 40% in base configurations to above 85–90% in hydrogen-boosted cases. Methanol production costs for waste-oil pathways are estimated at 650–1100 € t−1, depending on feedstock and plant scale, and remain lower than those of CO2-based e-methanol (1200–1500 € t−1). GHG emission reductions of 42–133% (RCF) and 84–232% (BIO) relative to the fossil comparator are achievable when concentrated CO2 streams are captured or renewable hydrogen is introduced, while FPBO pathways can enable net-negative emissions. However, the current RFNBO framework under RED III favors carbon origin over energy allocation, potentially disadvantaging hybrid waste-carbon pathways that achieve superior exergetic performance through RFNBO compliant-H2 integration, despite meeting or exceeding the GHG reduction thresholds required for compliance.