Challenging project to address critical issues with existing fitness app of our company

I have corporate wellness app called Flabuless which uses Google Fit for steps tracking. We have been using it for last 10 months and there are some very challenging issues that we need to address. - Users are required to download google fit app along with Flabuless which is not ideal. We need to build app in a way that it is not mandatory to download Google Fit. - If the gmail account is not in sync between Google Fit and Flabuless, then steps are not tracked. There is no way for user to be warned about this issue so he can avoid it. Currently, we show warning if there are no steps after few days of usage. - Google Fit App just hangs sometimes and doesn't work on few phones especially seen on Xiomi and need to be restarted to start tracking steps. If the user is travelling across locations then this issue happens as well. - Lot of users have complained that Google Fit tracks less steps than SHealth on their Samsung Phones. We have no ways to validate which one is correct. - Google fit sometimes reduces steps intraday. - Google Fit steps fetched by us do not match what shows to the user on Google Fit Screen. This is response from Google Fit - [login to view URL] Reason for using Google Fit was that we wanted to use one size that fits all Android phones. However, above challenges are making it very difficult to continue using Google Fit and we need a better and more stable solution. We may have to use different pedometer solution depending on device [login to view URL] example, Samsung Phones may use SHealth and Google Nexus may use its own inbuilt pedometer capabilities. This will be a two steps project. Step 1. I will have a detailed discussion on current deficiencies. Developer should then do the research and come back with technical solution to the issues. Step 2 After we agree on technical solution, developer can propose fixed cost for the project. Payment will be based on successfully meeting project milestones. Note - Sales representative of companies need not reply to this post. Companies may apply to this job. However, I would like to speak to senior technical mobile developer who can come back with technical solution to the listed issues