Tektro HD-M290, change to a dropbar lever configuration. Which levers are compatible?
The issue of cross-brand hydraulic lever-caliper compatibility has been discussed here previously. See this question and its answers: Hydraulic disc brake - lever compatibility. TLDR: no evidence for compatibility between brands.
Drop bar brake-only levers almost do not exist. All Shimano and SRAM drop bar levers integrate shifting and braking functions. The only product I know of is the TRP Hylex levers. These are designed for single-speed cyclocross bikes, which of course do not need gear shifting.
It's possible Tektro makes a similar product that is compatible with their brake calipers, but I could not find anything on their site.
What I would do is replace both the levers and calipers with TRP Hylex, and have the confidence that they are compatible and will not degrade or fail.