LuxCoreRender project is available on BountySource. It is a funding platform for open-source software. Users can improve the open-source projects they love by creating/collecting bounties and pledging to fundraisers. Check the BountySource FAQ for more information.
Salts are one time donation or recurring donations and can be done here. It is the most stable and solid way to support the project in the long run.
Bounties are a cash reward offered for development. In the case of BountySource, this ties directly to an open issue in the system at GitHub LuxCoreRender project page. Once you have created an issue on GitHub, you can create a bounty on BountySource to attract the attention of a developer. Several people can put bounties on the same issue in order to make the topic more attractive. Anyone is free to contribute and can hunt bounties, not just the core development team. This is intended to promote and increase the number of developers working on LuxCoreRender.