I agree with you. Hydrogen or algae based SAF's are the only real options in the shorter term for anything reaching medium haul stage lengths. At least until there is a massive weight reduction with solid state batteries.
Both have issues. Hydrogen doesn't yet have the infrastructure required. Nor the supply (but supply is even worse for SAF's, so equal footing there).
The premier downside with SAF's though is that I fear they will be a climate disaster prettied up as "green" tech. The only really valid source for carbon neutral alternate fuels is algae. The US and others are backing agriculture sectors instead however. This is skewing the price of what's needed to what's lobbied (and much worse). Agriculturally produced biofuels take far more energy to create, and land mass to use, for the given energy available in the end product. It's NOT carbon neutral. I've read about this over several years now, but this video by Real Engineering puts it very, very, well: https://youtu.be/OpEB6hCpIGM
The alternative is hydrogen then, which the EU and particularly France is pushing. It's in a sense a known technology. It's been tested and validated in aviation. With green energy used to create it it's essentially an entirely renewable and green fuel storage medium (I mean, you could make it with coal power, but that'd defeat the purpose). But this requires massive international investments in infrastructure. A slight upside is that you can run it either directly in traditional engines or through fuel cells for electric engines.
If I were Boeing I would be talking very seriously with Airbus about what direction to take. As two of the largest manufacturers in the west they can influence governments. And they will need to since they are reliant on something outside their field for the next generation of aircraft. The fuel and its infrastructure. Nothing they build until there is more clarity for the way forward can be expected to be particularly long lived. If they want sales numbers and longevity in the range of the 737 they need to take the future into account.
So aside from fuel, the question is if Boeing thinks it's valid to make a stop gap aircraft. One they know might need to be replaced completely a decade or two down the line.