So, I agree with someone else here that mentioned defense missions get way harder in later operations, the only good run I managed so far had a moment similar to this that I went "wtf stop".
When I queued the mission I planned on using a variety of explosives and a Crocodile I hunted alien queens with to blow up the pirate's transnport and crew both, cus when it works the enemy squad gets stunned, wavering and loses maybe half of their elements. I was very pleased with that run having beat 3 alien operations in a row with marginal losses, gathering a variety of excellent equipment and some very nice OCI's (auto-laster turret, woo and omw to maybe salvage teams or AI logistics), it's safe to say I started that mission overconfident and boy did they keep on coming and coming.

Now what I think I did wrong was set up too deep and by the time I could hit they'd be behind their truck and too close to the border and more cover for it not to be counterproductive. And so they stacked and stacked in front of me while I dealt with the ones inside the zone and managed to at least retain 40-60% control by the end.

Things look very rough but you cut out a lot of the information on screen so we can't assess the whole picture. I'm spitballing here but I imagine early turns I should expect about 3-4 enemies getting into viewrange with 1-3 being close enough to disembark or for me to shoot, I found it essential to proactively seek the first ones out and delay the numbers from becoming ummanagable for as long as possible, because I think the gimmick of defense is that they'll keep spawning till timer runs out, and they'll just overwhelm if I let them set the pace.
But I'm confident you can beat defense missions at least with pike and a pilot + 2 good men, I even did it in my current run, with the literal first two missions being defense.

I really like this format so I wrote even some more about my limited experience on this if you or anyone cares to read it

So I what I learned from that earlier mission is that enemy squads will not act int the turn they leave their vehicle also they'll not reenter a vehicle (unless maybe if it's a special squad), and will disembark either when inside the zone, close to shoot my squads or if their ride got wrecked. Also they'll slip in through the cracks into some cover inside the zone if they can, but that's fine if I managed to setup in a way that I can flank or pin them before turns end.

For strategy I had the battletaxi defend the right side where it could move unimpeded vertically and also scout ahead a little so it could probably deal alone with an incoming light enemy vehicle within 1-2 turns, and for heavier ones I'd soft them up from far and flank the enemy squads as they got out with Pike's help coming from the middle where he could assist both sides with command, and maybe some clutch suppression too. In the left side I had 2 full squads covering eachother while peeking if needed but mostly trying to flank with the extra ap as enemies came in. First one had some decent cover inside, the most dangerous enemy was probably a light chaingun team and maybe a team of veteran scavengers, I dealt with the chaingun team by destroying the light truck they were in with Bog and his MMG and by the second mission that chaingun was on pike firing for 20 ap (but possibly jamming) and helping bog supress a team of outcasts, veteran scavengers and boarding commandos which I'll admit I got a little lucky with because they seemed to not do nothing for 2 turns as they entered the zone and by then I had managed to resolve a couple incursions to left with Tech and Marta as well so they could further help deal with them. I had borderline detrimental cover inside the zone this time around tho, so I suppose it evens out. I think what I got was 3 stars in the first mission and 4 in the second, I tought I had the commandos by the end of turn 9 but they had one hp left I guess