I recall that earlier (over 10 years ago), producing a standalone compiler of LaTeX3 code was a project's goal. Today, this goal is no more articulated. Instead, the developers stress today that LaTeX is "not a stand-alone typesetting program". While there may be valid technical reasons for either decision, it is not my question here. My question is whether the goal of producing a standalone LaTeX3 compiler (which works independently of TeX/LaTeX2e) has been given up.
The LaTeX team are macro programmers, and the aim of LaTeX3 work has therefore always been in the form either of packages or a stand-alone TeX format. Work over many years suggests that to delivery for users today, creating code which is loadable as LaTeX2e packages is most productive. That does not mean a new format is ruled out. However, a lot of materials is likely to be added in package mode first. For example, we are currently working on tagged PDF: this needs to work now, and thus has to integrate into LaTeX2e. (This material is also going to be available in any future stand-alone format.)
It is probably more likely/easy for the team to provide 'tools' (binaries or scripts) than was the case in the past: see for example
l3build. That stems from the availability of Lua in all modern TeX systems as a scripting set up.