My guess is in military terms there is little Saudi can do to help Pakistan, as it's US and European aircraft are not integrated into our air defence systems and US aircraft will require permission. I think Saudi funding will help Pakistan armed forces a lot
My guess is there will be a symbolic Saudi presence
1) 1 Sqd of Typhoons, probably based at CCS
2) One Saudi Frigate at Gwadar
3) One Saudi Battalion (possibly even Brigade)
This will be symbolic as any attack on Pakistan will be an attack on these assets, also note that Saudi have sent ships, Fighter jets and armoured units to Pakistan on a regular basis for exercises, so this deal may just make these a permanent fixture
Pakistan presence in Saudi
1) 1 Sqd of F-16s that can be intgrated in RSAF air defence system
2) One PN Sub/Frigate at Saudi Red Sea base
3) One armoured Brigade
All of the above can play little role in defending Saudi in case of Israeli strike but the point is it will mean any attack will involve Pakistani forces defending Saudi. As with Saudi, Pak ships, brigades and fighter jets are a regular fixture in Saudi so this would just make them permanent
Essentially this deal is strategic in nature, practically each side can do little at the moment to militarily protect each other, but for Saudi it means a nuclear armed nation coming to it;s aid. Pakistans benefit may well be more financial in terms of funding f defence equipment purchases as there is very little Saudi forces can do to help Pakistan in war against India
Juts my thoughts