At 7 years old, if your dd is omitting final sounds her speech intelligibility is likely to be very poor, with a disorder within the severe range. Whether this is called dyspraxia or severe phonological disorder or inconsistent phonological disorder is only of marginal importance. In all cases, at 7, she needs intensive speech and language therapy input using a structured programme in order to make progress. This would be true even if she didn't have ASD.
In addition to this she needs a suitable alternative or augmentative communication advice. Contrary to what people sometimes think, AAC is not a poor man's substitute for speech therapy - it's actually pretty vital.
The key to everything in speech, language and communication disorders is isolating what needs to be worked on, working on it intensively and systematically and ensuring frequent opportunities for that skill to be used functionally. While speech may present as the most pressing issue, I can almost guarantee you that if your daughter is struggling to communicate because her speech is unintelligible, this will reduce her opportunities to use language and to communicate with others which will have a knock-on effect across all domains of speech and language.
In the Nuffield programme (as you may know) targets are multilevel and multitarget so you are working on lots of different things at the same time e.g.
k - single sound level
b - cv level (ob, ib, ub etc)
d, t, s - cvcv level (and here you can have same or alternating vowels so split it further e.g. tata or tatee etc).
then cvc, ccvc, cvcc and multisyllabic targets, then including these in sentences etc.
In the same way, you can have spoken language/communication targets that are multilevel and multitarget. I can't give extremely effective examples because I don't know your daughter. However, with the secondary students I work with, some of them would use AAC only for very specific reasons e.g. in science lessons where certain multisyllabics are too challenging in speech, but they would try these through low tech means first e.g. writing/drawing, using AAC as the final resort. The rest of their communication would be speech only. Typically higher tech AAC is used more frequently by my clients with non-familiar people or in non-familiar situations where a transaction has to happen more quickly than they have strategies to manage e.g. on the bus where there may be queuing and it's too hard to get across that you need extra time (and you probably won't be given it anyway).
What this means is that if your daughter can communicate some things effectively in speech only, these don't need to be targeted with a high tech AAC device. However, without an AAC device and given the rate of progress with severe disorders of this type, if she doesn't have AAC it is likely that there will be things that are beyond her ability to currently communicate. If she can't do it with speech and has no other options, opportunities to say things or to practice language skills may be unnecessarily limited. Someone with very unintelligible speech as their primary issue may be able to string words together in sentences but because they are poorly comprehended by listeners, there is no motivation to really persist with this and the person will almost always reduce the complexity of their language to get a message across. This may still be true for your daughter, or like some other children with ASD/dyspraxia, she may not realise and just power on and not really even realise that people aren't understanding her which in itself is not helpful.
It's all interlinked. AAC is not perfect, it has a long way to go and it requires extremely careful planning to be used effectively alongside speech programmes but if it were my child, I would be very insistent on it AND appropriately intensive speech therapy. I have unfortunately seen the fall out of intensive focus on speech only and even where speech has almost resolved at secondary, there is still fall out if language and communication haven't also been prioritised.
For dyspraxia or severe speech disorders, optimum input is something like about about 2-3 hours of therapy a week and daily carryover of 20 mins with someone following through in class and at home. This is usually only achievable in specialist speech and language units and unfortunately access to these is erratic.
Hope this helps.