I've written another Xposed module for my LEX720 for a very specific purpose, so probably it won't be of much use for the most. But I'm still publishing it for reference reasons.
First the good news: The stock firmware of LeEco includes the "SmardcardService" (which also often is referred to as "Open Mobile API" or short "OMAPI") which is an extension API to plain Android (i.e. not existing in the Nexus devices or the Pixels) to allow apps accessing Secure Elements (i.e. secure applications embedded in a tamper-resistant hardware) within the SIM-card.
A real world example: in Austria some banks (in cooperation with the 3 largest network operators) support Tap'n'Pay with your phone by installing the NFC-capable banking card as an additional application into the SIM card (which is the same secure chipcard technology as a banking card). This means you get a new SIM card and then you can tap'n'pay with your phone (without Google, without VISA or MasterCard, just as with the Austrian NFC banking cards). AFAIK in some other countries the same concept is used for public transport and others.
The main difference to Android Pay is, that this system is backed by the chipcard (the SIM) and not by a cloud service. But this just as background information.
The LEX720 is a dual-sim phone, and so the (banking) apps could read SIM-cards from either SIM1 or SIM2 slot (I tested, SmartcardService works with both). But if you also want to use NFC for payment it has to be inserted into SIM1 (as it seems that only the SIM1 slot ist connected over an SWP line to the NFC chipset). Unfortunately the Austrian banking apps don't seem to handle the dual-SIM situation correctly and only try to read SIM2 (which is empty for me) and therefore don't work.
Additionally, at the end of an transaction, when the application running within the SIM card signalizes that it just had finished a payment transaction to the Android system, the NFC service (/system/vendor/app/NQNfcNci/NQNfcNci.apk) broadcasts this message as an intent to the relevant (banking) app, so that the app can display a transaction result activity.
Unfortunately this mechanism is implemented often very different by different OEMs and so also by LeEco. There exists a standard (GSMA NFC Handset APIs Requirement Specification) but it seems there are a lot of different implementations in the wild.
(Note: this is probably the case because this type of functionality is not part of the official reference Android source code. Plain open source Android like it is running on all Nexus phones and the Pixels just doesn't support these type of applications - which is very unfortunate).
TL;DR I just made an Xposed module which fixes these 2 issues for me. Look into the README on Github for more details.
Source on Github: https://github.com/johnzweng/XposedOmapiBankcardFix
Download Xposed Module: Xposed-module-OMAPI-BankcardMobil-Fix-1.1.apk
Maybe it's also useful for other applications which use the SIM card as secure storage for keys of any type. Use at your own risk.
As a reference: these are the Austrian banking apps this module should work with:
- Bank Austria Mobile Geldbörse
- BankCard Mobil
- Oberbank Bankomatkarte Mobil
- Raiffeisen ELBA-pay
- VKB-Pay - Bankomatkarte mobil
Updated download link to version 1.1.
For details see the CHANGELOG in the Github repoistory.