I really like the ESP+LD2410C combo. DIY is about $5 for the ESP and sensor but you’ll need to figure out a case. If you have a 3D printer, access to one, or are willing to use a service, they can be printed. I have model files for using either an S2 Mini or C3 Supermini on Printables. Alternatively, you can buy preconfigured ones from SCREEK. The downside is no zones (if that’s a requirement) and a bit of tweaking to get the sensitivity dialed in. There’s plenty of folks that can help with the latter.
The Tuya sensors are alright, but their lack of sensitivity adjustment means you have to experiment quite a bit with placement. They are extremely chatty so get a few going and you may run into stability issues if you go the ZigBee route.
I have an FP2 but honestly haven’t messed with it much since I don’t have a use for the zone functions.
EDIT: just saw you mentioned printing cases. Here’s my page on Printables with the models for the two setups I mentioned above.