You do realise that the E-V13 branches in Albanians start to diversify usually about 500 years (!) or more later than in Slavs? That means among Albanians, many of the branches had by 400-900 AD only one single founder, whereas some of the Slavic branches had multiple surviving ones. And that's despite the worse testing frequency. If e.g. Slovaks and Ukrainians would be tested like Albanians, how do you think things which shift then?
With Albanians its like it is with I2a-din and E-L540, we don't know what their base was before the founding event. We don't know whether they were Pre-/Proto-Albanian, we don't know whether they had many side branches which got lost during the Late Antiquity bottleneck, we just see fairly late (no earlier than Late Antiquity, many Slavic era) founders.
I'm rather agnostic on their past at the moment, I'm just sure about their presence, and that is they had indeed a fairly recent founder event.
E-L540 might very well have been Germanic, but it was taken up by Slavs, fairly early on. We don't have such late, huge founder events for most Germanic branches, that looks odd. And again, we have the data-rumours for Eastern Germany and the area, it seems Western Slavic tribes had higher frequencies of E-L540 which moved into nowadays Germany.
And its not just E-L540, but e.g. branches like
https://discover.familytreedna.com/y-dna/E-FT256723/tree (or
https://www.yfull.com/tree/E-Y255338/ ) and parallel ones to it. They start to diversify within the Slavs (exclusively Slavic testers) in the 1st century the latest, just like E-L540.
You know there are some Albanian branches to compare with, much better tested than these Slavs, but while they are nowadays very widespread, their TMRCA is 600 years later:
www.yfull.com
That doesn't tell us how long they lived in or around Albania, could have been much earlier, but it proves a recent founder event after a potential bottleneck in Late Antiquity.
And you know that E-S2979 is the central group I associate with the Dacians, it is totally dominant in the Avar era samples and we find it as far as China on the steppe highway.
Also, we need to define "Proto-stages" for both Slavs and Albanians, because for both we deal with a Late Antiquity Proto-stage still. Therefore if say both in Slavs and Albanians some Dacian E-V13 branches entered the population in Antiquity (say 300 AD, with the Dacian resettlement), they became part of the Proto-stage for both.
That would be the best explanation for Slavs also, why they consistently and constantly have E-V13 at a low rate in all early samples we got, in the Medieval period, from Northern Germany, Eastern Germany, Poland, Russia etc. If they entered the Slavic population before 500 AD, they were part of the Proto-stage, regardless of where they were before. Same goes for Albanians, by the way, because just like with Slavs, it lasted well into Late Antiquity:
https://en.wikipedia.org/wiki/Proto-Albanian_language vs.
https://en.wikipedia.org/wiki/Proto-Slavic_language
Both began to split and leave the Proto-stage around the same time, which is 600 AD. Note the Albanian branches diversify usually not much earlier, but some Slavic do, which just means they recovered, grew earlier, not that they had to be absent from Proto-Alb.
In both cases we don't know at which stage E-V13 became part of the Pre-Albanian/Pre-Slavic people or just later. For Slavs we can say the Pre-Slavic stage is still Baltoslavic and E-V13 is not Baltoslavic, even if some Balts got E-V13, it seems to be mostly transmitted by non-Balts later. Therefore for Slavs we can say no earlier than the Proto-Slavic stage, for Albanians/Albania we don't know. Could be earlier (even LBA) or as late as the first proven diversifications.