What an intriguing and fascinating breakdown.I probably need to preface this by stating the fact that the only truly Ethiopianist ethnic groups in Ethiopia are the Amhara and all the small micro groups that cannot hope to fend for themselves without the existence of "Ethiopia". The rest like the Tigrayans (TPLF), Oromos (Prosperity|Poverty Party/Abiy Ahmed) etc are just opportunists looking to enrich themselves. Ethiopia is just a cash cow waiting to be milked.
That being said, a Tigrayan administration (or more specifically a TPLF administration) adds a more dangerous complexity to the Eritrea-Ethiopia feud. The Tigrayans are staunch ethnonationalists. Their plan has always been to stuff their pockets full of cash and develop their kilil and when the time is right: secede and join their "Tigrayan brothers" to the north. To them, Eritrea is simply a Tigrayan state (even though the Kebessa have never identified as Tigrayans in history) where they can simply join at the drop of a hat and supplant Tigrayan hegemony. The issue is that this sentiment is not reciprocated at all. It is very much an unrequited love affair. Eritrean civic nationalism and Tigrayan ethnonationalism are two irreconcilable philosophies. The only way to destroy the former is to tear apart the social fabric in Eritrea that transcends ethnic groups. That's why when Ethiopia was under TPLF administration, they hosted and funded a number of Eritrean ethnic militias (RSADO, DMLEK, SPDM etc). They have been trying to awaken an "Tigrayan ethnic consciousness" within the Tigrinya of Eritrea that simply doesn't exist. It also why during the war in Tigray, TPLF associated media outlets shamelessly purported that the atrocities allegedly committed in Tigray by Eritrean forces were predominantly done by Beni-Amer and Tigre (not to be confused with Tigrayan) soldiers of whom were identified by the tribal scarring on their faces. These bogus allegations were made with the sole purpose of trying to fuel Islamophobia and Tigrinya-chauvinism within Eritrea.
In short: Abiy wants to conquer Eritrea. Tigrayans want to destroy it