First of all you need to respect what is agreed between the company and the researcher. Usually there is a written contract. Some companies allow publication, others don't. Some have a specific policy about the licenses under which the research results may be published.
Usually, the copyright is owned by the one who pays. In the case you describe it seems to be the company who pays, therefore they need to be given the copyright attribution. The agreement between company and researcher might give some rights to the researcher, a license, possibly with sub-licensing rights. That should be part of the agreement.
In some cases there is a joint funding (public and private) for the researcher. Research foundations, subsidies for companies, innovation partnerships, research grants Schemes, etc. where part of the pay for the researcher comes from the public sources. These settings have their own rules about ownership of the work product, and the rules are very country-specific.
After considering all of the above, it will be clear how a publication on GitHub can be done, who owns the copyright, who owns the right to apply for patents, which OSS licenses may (or may not) be used. There is no 'one size fits all' rule. You should ask the legal department of the company which employs you as a researcher to provide you with all the relevant documents.