I’m 10 DPO from full TT, muscle repair and Lipo to flanks. Is tummy supposed to be firm right after a tummy tuck? (photo)

Firmness and hardness are subjective terms.  The photo you provided is still early and has a great deal of swelling.  This may produce an outstanding result if you were to fast forward 3 months.  Some PSs produce very flat, very tight-looking results, whereas others are more conservative in the amounts of skin and fat they take out. Rather than compare your recovery to others, I would continue to follow your PS's post operative guidelines and follow up with him/her to allay your concerns.

Swelling and bruising are common after a tummy tuck and can take several weeks to resolve. If you do have a seroma it can typically be addressed in your surgeon's office. It is not always associated with fever or pain. It's best to visit with your surgeon who can help determine if there is a cause for concern.

Hello dear!!
Thanks for the question and provided information as well.
You are still early on the healing process, it can take up to six months to see your final results, so please be patient. At the stage you are in, inflammation is normal. It is not suppose to be firm right after surgery.
If you have any concerns, please follow up close with your plastic surgeon.
Good luck :)

As you can imagine, it's very hard to give you a diagnosis based on your description of what your tummy feels like to you.  Even when personally examining a patient it's not always easy to know what's going on every time.  What you are experiencing can be perfectly normal at this point so early in your recovery.  When fluid is present as in a seroma, the tissue will wave when pressed, it's very obvious. Softness in the tissue may indicate swelling.  At this point you'r entitled to have swelling.  If you're concerned about your results then ask your surgeon, he/she will be happy to explain what's going on. 

10 days after surgery still very early to judge outcome. Swelling, bruising, firmness are all expected during this early stage. Please relax and offer more time for things to settle. 

Hi and welcome to our forum!
From the before / after pic, it appears that the early result is excellent! 
There are several factors which influence superficial tightness (of the skin and soft tissue) after abdominoplasty  including swelling which should at this time totally obscure the result, the presence of abdominal subcutaneous fat (which is not removed by abdominoplasty), or the presence of residual stretch marks which indicates damage to the elastic fibers of the dermis and will result in a degree of restretching. Deep tightness depends upon the rectus muscle repair (Remember that all abdomens are loose when sitting and tighten upon standing).
Fluid beneath the flaps (seroma) requires attention. A fluid wave may be noted as you turn from side to side when in bed. You may see or feel the fluid move under the skin. If this is noted, see your plastic surgeon as soon as feasible as you may require treatment.
Be patient...as it takes 6 weeks for 60-80% of swelling to subside and 6-12 months to completely abate, you have a way to go.
Continue followup with your plastic surgeon.
Best wishes.