5G not yet, it's only rolled out in the centres of Buenos Aires and Rosario so far. Coverage maps for 2-4G here: https://www.nperf.com/en/map/AR/-/-/signal/I am envious of rural argentina, if they get 5g. Here in rural Washington State, I am lucky to get 1 bar of 4g.
The distinction between fixed and mobile, often, is price.
And yes, given that mobile is fast enough now, the difference between fixed and mobile for the user is price. FWA packages would be priced as fixed connections. Some of this is happening now, some is yet to come.