The smallest I have is a 6 x 13 wonky shaped fiberglass pool and the largest pool I think is 8 x 18.  

Here is the basic timeline:- Purchased property in late 2019 for $490,000- Property was a 2 story 4 bed/2.5 bath house with a full unfinished walkout basement- Premium for the property compared to one without the walkout was somewhere around $30-40,000- Basement was around 1200sqft unfinished space and the apartment was best setup to be around 800sqft- Started initial framing in early 2020, but COVID put a stop to some plans due to cash reserves becoming more important- Project was on hold until late 2021 when framing resumed (all framing was done by me)- Jan 2022 had a tankless water heater installed (had 20 year old tank already and don't want to run out of hot water with tenants) $3500- Jan 2022 had main electrical panel upgraded to 200A setup and also had 100A sub panel installed in basement and charger for car in garage $6000- Feb 2022 finished 95% of framing and GC began plumbing work- Feb 2022 HVAC work began (We installed a fully separate Mini Split Heat Pump for the unit) $5,400 for all fans and mini split install- March 2022 Electrical Rough In was completed- March 2022 Rear Door (Entrance) was swapped from a small slider to a full 36" exterior door- March 2022 Passed rough inspections and given the go ahead for drywall- Late March 2022 Drywall install completed- Walls are standard 1/2" single sheet- Ceilings were done in the following order for sound insulation (Fiberglass batting, resilient channel, 5/8" drywall, Green Glue, 5/8" drywall) $7500- April 2022 Primed all walls and ceiling- April 2022 Carpet and Vinyl flooring installed- April 2022 Trim installed- April 2022 Kitchen cabinets installed- Mid April 2022 Interior doors arrived and were installed- Mid April 2022 Shower pan was built out- Mid April 2022 Butcherblock counters cut and fitted with sink and oiled- Mid April 2022 Puck lighting installed- Late April 2022 Appliances arrived- Late April 2022 Painting continues (biggest regret here was not hiring a painter.

That looks like a fiberglass drop in right?  

We’re highly considering a fiberglass pool over concrete due to installation timeframe and about half the cost of concrete.

It did not 'soundproof' the spaces, but I think it probably reduced the sound transfer as well as a larger space with regular r-13 fiberglass batting would have deadened the noise.

Installing acomposition fiberglass or asphalt roof in the future will require the additional expense of installing sheathing, such as plywood or oriented strand board (OSB) over the batten boards.26) One or more flashings for roof penetrations are installed in a substandard way.

As for the shower/tub surround, are you thinking tile or a prefabricated fiberglass surround? 

Remove all the skin and replace it with fiber glass to make it lighter.

If I have to use an acrylic or a fiberglass tub, it's usually customer supplied. best advice with those is to bed them with structolite underneath or they will crack eventually.In my experience chips usually aren't a manufacturer's defect but are the fault of negligent installers or people who drop tools on them. 

Does refinishing/reglazing work for fiberglass?