Hi Rashi,
Have you tried playing with Clay? It seems like with that tehc-stack you're paying double efforts platforms.
If you have Apollo they work as email sequencer as well, otherwise Clay can help you with finding leads and integrates perfectly with Instantly. With clay you can build the personalisation and you can find work emails and phone numbers across different providers with validation.
This is my humble opinion, you could manage your GTM on one platform and work with the sequence with instantly.
Also which one is your CRM? that plays a good role in how you're keeping your data clean
