There’s no deity worthy of worship but Allah*
“Allah” comes from the stem word “ilaah” + Alif laam
Roughly translating to “the ilaah” (the worshipped)
He worshipped, worships, a worshipped enity
Claiming Allah is One without claiming that He is worthy of worship will not save one from His wrath.
The word ya’lahu (to worship) itself carries many meanings, from them being “turning to” “showing reverence to” “trusting” “relying on” etc, and those are all forms of worship to Allah subhanahu wa ta’ala! سبحان الله.
Many of today’s mushrikin believe Allah is One, and that there is none with exactly similar power to Him; yet they still sought others in worship (du’a for example) therefore becoming mushrikin and making Jahannam their eternal abode.
Tawhīd is three parts, two of them lead to the Tawhīd of “worship” or Tawhīd al Uluhiyyah, for the fact that Allah is the Rabb (from tawhīd al rubūbiyyah) and the fact that we acknowledge His names and attributes (asma’ and sifaat) makes Him worthy to he worshipped!
For the Rabb (the sustainer the creator the owner etc etc) and the owner of those great names and attributes with which He showers us in blessings and rules upon us with qist (justice) and Rahma, such entity surely deserves to be worshipped, and this is known by fitra! Therefore, if you acknowledge Tawhid al ruboobiyyah and Tawhid al Asmaa wa al Sifaat you will automatically find yourself leaning towards Allah in worship (towards tawhīd al Uluhiyyah)
And the other way around too, when you say “there’s no deity worthy of worship besides Allah” (tawhīd al Uluhiyyah) you are just with these counted words saying that you also believe in His rubūbiyyah and His asmaa and sifaat (so you’re a believer unless you commit a nullifier) for you would not worship Him unless He were the creator and the sustainer and the most merciful and compassionate etc etc, in easier terms, you would not worship Him if you did not believe in His rubūbiyyah and Asmaa and Sifaat (obviously unless you have a shubha or flawed ta’wil but this isn’t our point here)
What a beautiful word La Ilaha Illa Allah is, the separation between islam and Shirk, and How merciful is Allah that He summarised His entire religion in a sentence of 5 words!