Without getting into the weeds of programming for the secure element (some non-EEA markets only, NDAs, tons of certifications etc.) or restricting yourself to HCE (available only in the EEA), you could also "flip the model around":
ISO 14443 reader access has been available globally, so if you're fine with having to open an app before an interaction with a reader, you could have the reader perform card emulation, and the phone "read/write" it like a tag, i.e. send APDUs which the device behind it then interprets.
ISO 14443 reader access has been available globally, so if you're fine with having to open an app before an interaction with a reader, you could have the reader perform card emulation, and the phone "read/write" it like a tag, i.e. send APDUs which the device behind it then interprets.