Integrate curated provider list
To make onboarding easier, a curated list of providers can be of great help. The XMPP Providers project provides a curated and machine-readable list of providers, complemented by various provider infos (e.g. compliance rating, MAM storage time, file retention time, ...).
The list is available in JSON and can be filtered by country / suggestions based on IP / device language.
The repository provides a script, which yields three categories from the list.
Category A has the best ranking and also only list servers which support IBR (in-band registration). The output lists only the servers and no details. If it is of interest to make use of some details, those need to be exported as well. Providers listed on Category C might contain servers with bad properties of any kind (it's not recommended to take the bare list).
For Gajim it would probably be best to host the list where it can easily be updated from time to time. The Account Creation Assistant can then update the list if the user wants to.
Here is an example of the integration in UWPX: