For practising buoancy as well as finning skills there is little a "destination" will do for you over a local pool or lake (a bit early for the latter). With a scuba diver cert. you can practice with a dive master in the water with you ... or an instructor of course. Taking your time and just practising to hover calmly a couple of feet above the floor (as a reference for good trim) and then experimenting with breathing a little deeper and a little less deep to change depth a bit goes a long way. Take a few hours of pool practise time locally if you can find it guided if you wish, but w/o pressure to need to achieve something right now. Give yourself the time to feel it. Once the pressure is off you will.
Of course flying somewhere to train with a particular instructor is not wrong either, but then the pressure is on again. At that particular time you have to be healthy the instructor has to be healthy, you have a time limit... etc...
Once you are comfortable hovering horizontally at a depth in the pool and can change your depth and then hover (no forward propulsion) there,
.. really, your buoancy is quite good. If you can do that and you passed all the skills to get the scuba diver cert., you definitely can finish the OW cert. ... at home once warm enough or anywhere you want to.
My wive was struggling during OW in FL in wonderful warm water with good visibility. Not a natural in the water. She also came home with a scuba diver rating. Back home, after a couple of months of break, she finshed her OW training in a local quarry with cold water and 5' to 15' visibility (pending where). The instructor praised her sky high.
She wasn't diving that good, always at a trim of 20... 30 degree inclined, but the praise, patience and confidence building did the trick for her to get through...
Since then we practiced hovering and diving over and around a platform once (two half hour dives) and it slowly got a little better. Nothing since October.
A couple weeks ago she dared to go to pool practice with me. Out of the blue she was in horizontal trim. Just like that. Maybe because she started in 4' of water and getting anywhere there does not work well unless horizontal. Maybe because prior stuff sunk in. Maybe because she could see herself in a mirror I brought and hung... No idea. But she fees the practice helped and she feels she could tell a difference. So could I and others...
Long story short: Pool practice with aim on trim and buoancy is good. better if with feedback. The floor as reference below you is your friend to figure out if you are horizontally trimmed. You do not necessarily feel it at first. You may need the reference. A mirror might be helpful too (it's not necessary, but instant & self witnessed feedback helps a lot more than a hubby or friend or instructor trying to tell you what you did, when in your head you think you know it was not so... ) Mirrors don't lie.
Edit 1: P.S. I am neither an instructor nor a DM...
Convex mirror works well for instant feedback
Edit 2: This thread may be interestin to you & ser page 10...
Maintaining Trim while motionless