Glued down engineered is the only way engineered should be done over slab. If you pick wisely, and care for it properly, it is a 60 year floor. However, hydronic heat and a warm enough climate to require a slab foundation is double the hvac expense for poor control and a lagging response. And, you get knocked out of having any but the most expensive wood, as most wood is incompatible with most hydronic. If you live in a cold enough location that your heat stays on for 9 months, and you don’t need AC, then pouring a slab just to have radiant is also flawed thinking and an unneeded additional expense. You really ought to be using tile for sure then, if you’re going to the expense of a slab for radiant. Wood is an insulator against heat transmission. . Or skip the ultimate 100K add on hydronic upgrade.

Smart Core Naturals that you can see at Lowes, Geowood and others use SPC core with wood veneer as the wear layer. These would work for hydronics without regard to wood species. Flooret has a Swedish product, Silvan Hardwood,

We had this in our mountain home, over a slab with engineered wood - and LOVED it (it was glued down). Yes, it was more expensive up front, but I’d do it again in a heartbeat. We didn’t need AC - that was key. We did have to have an ERV unit (we also had foam insulation). They ran it up to the 2nd floor and encased the tubes in Gypcrete. The warranty on the wood floor insisted on a whole house humidifier (we are in CO - very dry). The utter silence of the heating system is gold - no vents to get crap down into either. The only thing I would have done differently is put a separate thermostat on the primary bathroom - so you can keep the bedroom cool and the bathroom a bit warmer. Had to plan ahead if we were going to use guest bedrooms, as it takes hours to heat up, but that wasn’t ever a problem.