OSS means 'open source software' and to make a point I often call it 'peer reviewed open source software' because only this software has a scientific integrity. The entire Enterprise Hardened Gentoo backed here at TDO is made up of this open source software. You can also open source software at the web application level, where things have already been done. This service is about deploying it for you to do the administration and customisation of its configuration yourself.
I can install many things for you and for only a upfront cost of $20 AUD. If it is written for an open source web framework in the Gentoo ecosystem such as Ruby, Python WSGI, PHP, Composer, and far more I can deploy it. You do need a Shared Web Stack basic service and this does not cover deployments on a targeted strict server, which are far more complicated. I cannot assure reliability of this software but can faithfully install the requested version branch and release your desire. If you don't know what release and version you want I will just install what seems stable.
Since the shared web server is an nginx stack deployed software can have limiting aspects in regard to webserver configuration. Clean URLs with PHP for example may require additional configuration. I can't give an absolute price on what that would cost for every web application. With popular web software there is often an nginx configuration I can crowdsource that gets it working smoothly. One can submit an nginx configuration for my review and installation. Unfortunately nginx was designed in such a way that users cannot control the webserver configuration themselves.
Also if you are a community service and for a good cause, and are not-for-profit and actually help people I may provide installation and hosting resources for free. Just let me know what you are about and what the site is for and who it is going to help. Such sites however if they become demanding and consuming may have to be monetized. I can do that for organisations and direct them towards things like advertising and fundraisers to cover expenses. If your community site is monetized I am the recipient of the funds.